The Highline Trail through the Uintas is a pretty good hike; a bit of a classic, if under-utilized by the hiking community overall (which actually contributes to its greatness, if you ask me.) The actual full trail is 104 miles long, according to Wikipedia, although most who hike it don't start (or finish, depending on which direction they go) at the true eastern terminus, but rather at one of two alternate points further along, meaning that most do either the Chepeta to Highline portion (62 miles) or Hacking Lake/Leidy Peak to Highline (78 miles)—both of which are still pretty darn worthy backpacking trip goals.
And although I'm not in shape to do this myself, I've long been a bit saddened when looking at a map of the Uinta Range and seeing that the Highline Trail really only does a portion of what's available. Sure, it may be the classic portion. It may be the best of. But what if you truly wanted to traverse the entire range? On caltopo, I drew a straight, unhikeable "as the crow flies" route more or less along the crest, and I got a total of 160 miles; quite a bit more than the Highline offers. There's the entire Western Uintas roadless area between the Highline Trailhead on 191 and Kamas, the valley that truly marks the western end of the Uintas. And east of even the lightly used eastern extension of the official trail, the range continues eastward through Flaming Gorge National Recreation Area and Dinosaur National Monument all the way to Cross Mountain just east of where the Yampa and Little Snake rivers split.
I've put together (also on caltopo) a route that purports to traverse the entire range from a dirt road junction just east of Cross Mountain to Yellowpine Trailhead; the farthest west on the Mirror Lake Hwy, and just barely past the small "suburb" of Samak just outside of Kamas. Here's the actual map, divided into four convenient and color-coded sections. Well, technically six, but I'll get to the fifth and sixth ones in a moment. The actual route, if hiked as mapped, comes to 235.34 miles—quite the epic adventure, and worth almost three weeks of backpacking for most—although really fast hikers could probably get that at under two.
Interestingly, according to the caltopo map, almost the entire section of the range east of the Green River canyon is part of a single massive (although low and rounded) mountain called Douglas Mountain. I also added a work-around, just in case the canyon proves to be completely non-navigable. Given that it looks to have about a 45° slope on the Zenobia Creek canyon (and not much better on the way up for Pot Creek) it might be; but the workaround adds at least a day's worth of hiking, and goes all the way to Brown's Park; the big valley just north of this part of the Uintas, before diving back in at another entry point.
Going from west to east, the sections are:
The West Extension. (dark blue) This is stitched together from existing trails, with some very small areas of bushwhacking required. The trails are typically fairly well covered, well traveled, and even many of the so-called bushwhacking sections are frequently done by hikers in the region. This area is more known for its Boy Scout camping, fishing, and car-camping than extremely remote backpacking, although the route should be far enough removed from the most famous fishing holes and the Mirror Lake Highway itself that crowds aren't too bad. This should be an easy section to travel for most; two days (only one night out) for extremely fast or strong hikers, but better off with two nights out, giving you up to three days to traverse this section. At its easternmost section, it does require a little bit (considerably less than a mile) of roadwalking along 150 to get to the Highline Trailhead. 28.55 miles.
The Classic Highline. (red) This is the classic highline trail; going from Highline Trailhead to the Leidy Peak trailhead at Hacking Lake No. 2 far to the east. I've added a few minor detours, including taking the northernmost option of the many trails that cross Rock Creek Basin, going off trail for a small detour to see Reconnaissance Lake, taking another small detour near Red Knob Pass to see Crater Lake, and of course, the traditional summiting of Kings Peak when you're already right there on Anderson Pass just a little over half a mile to the north. I've also gone off the main throughput on to some other trails to see the Red Castle area, since you'll be passing right to the south of it anyway. Altogether, this section of trail is listed as 91.57 miles, and would take over a week for most to hike given the terrain. I'd plan 7-8 days, ideally.
Highline East. (orange) Technically this is part of the trail, but traditionally its rarely been done, and until very recently, reports were that the trail was in very bad condition, hard to follow, often faint, etc. and that it doesn't go through the dramatic scenery, so it wasn't worth the trouble. It's a bit lower elevation, and none of it is above treeline. Although it isn't just forest hiking; it does go through a number of reportedly very pretty "parks" or open meadows, and you can see Leidy Peak for miles as you hike it, it's the red-headed step-child of the trail; usually ignored. Many who hike the trail don't even believe that it is officially part of the trail, or know about it. The Trails Illustrated map of the High Uintas Wilderness stops right about where it starts, and you need the next map to the east (Flaming Gorge) to even see it. But some volunteers in nearby Vernal have apparently decided that the deplorable trail conditions were a bit of an embarrassment, and supposedly the trail is now fairly clear, having had a lot of work done to make it navigable. This section is also only 24.99 miles, according to my caltopo line. If the reports about better trail conditions are accurate, this can probably be done in two days, if you start early enough.
Uncertain Eastern Section. (light blue) This part is the interesting one, and as far as I know, nobody hikes a route anywhere close to this. I stitched it together mostly from jeep trails and other very poor quality dirt roads, which turns many hikers off, I presume. It also does include a little bit of bushwhacking (some of which could potentially be avoided) but not much—although the trickiest part would be the plunge from Zenobia Peak down Zenobia Creek to the Green River in the Lodore Canyon, and then back up Pot Creek (or vice versa, depending on your direction of travel.) I honestly don't know if this is a doable route or not; I don't know if public access to these roads and trails is a given, I don't know if my bushwhacking is too extreme to be considered doable (especially that part I just mentioned) and I don't know if water availability makes it an extreme hazard. Given that you have to do the rest of the Uintas in the dead of summer, this lower, desert section of the Flaming Gorge and Dinosaur National Monument area might be too hot to be comfortable or advisable too. So far, it's merely a theoretical route that requires considerably more research to determine if it can really, truly be done or not. It's also quite long; at 90.23 miles, it's nearly half the traverse by itself.
Alternate Northside Route. (purple) This part is an alternate route through the western section of the High Uintas Wilderness part of the route. In theory, it's quite simple; it ditches the Highline Trail itself at Dead Horse Lake, and goes over Allsop Pass to see Allsop Lake, then hops over the next pass to see Norice and Priord Lake, goes around Amethyst Basin (maybe I should pop in to see that, actually—although it would require a detour.) Then it goes on into Middle Basin, on trails now, and then crosses the pass to reunite with the Highline Trail right about at its trailhead. Pretty much all of this route has been done, although not stitched together, as far as I know, but much of it is off-trail route-finding over sketchy passes, so it's a very advanced option. It just seems a shame to miss some of those stunningly beautiful mountain valleys on the north side of the main crest of the range when you're right there just on the south side of the main crest otherwise. Not that the south side of the range isn't also very pretty, but... y'know.
Alternative Douglas Mountain Area. (green) If the Green River canyon turns out to be unreasonable in terms of something I can hike down and then up again the other side, I can bail and, without losing very much distance, do this alternative instead. It's not necessarily desirable; I'm sure it adds at least another day, and it actually leaves the range to the north to skirt the entrance of the canyon (the justly famous Gates of Lodore) up in the Browns Park area, before diving back in again a little to the northwest. I'd actually like to see the Gates and Browns Park, but given how long this desert section is going to take as it is, I don't think adding another day is really ideal. But it may be unavoidable.