After HitR, consider backtracking to the Bear's Ears and taking the back scenic way to Canyonlands via Beef Basin. The only down side would be if there is significant snow this year, which can block the road right at the bears ears, or turn it into a quagmire of mud. This is about 2-3 days worth of travel and pretty spectacular. As a bonus, your outlet is over Elephant Hill and into the Needles district of Canyonlands NP. From there, it is possible to pick up the trail through Lockhart Basin which will take you all the way back to Moab, with some of the best scenery and remote travel anywhere. Or, you could just pick up pavement there, and make your way back to Moab on the highway.
Be aware though, we have been denied access in early May-you can ask
@beno about getting caught in the snow right around 2009 or so. Other years we've gone through in late April with dry conditions. One time the trail was fully blocked by a large downed tree-we could pick our way around but a large chainsaw would have been nice.
If you did the Elk Ridge/Beef Basin/Canyonlands/Lockhart that would take about 3-4 days depending on trail conditions.
Another option right in the HitR area would be to pick up the trail north into the Maze at Hite, and spend a few days in the Maze, going out to the Dollhouse if conditions allow. You need permits from the Park Service and they enforce it. You can call the Han Flat ranger station to make sure the Flint trail is passable so you have a way out to fuel at the end. That would dump you out in Green River on I-70-perfect for getting back to SLC. Just be aware that the Maze is even more remote, and has no water, and that time of year likely no people either. If you can get Dollhouse 1&2 campsites they are the best. "Maze Overlook" is also spectacular.
You can also get into the Maze via Poison Springs (pick up the trail between Hite and Hanksville). Very spectacular scenery, but it could be difficult to cross the Dirty Devil River if there's a lot of runoff. If you know where to look, lots of great petroglyphs on the first part of this trail, and after the river crossing the scenery is magical all the way to Sunset Pass and into the Maze.
One last idea would be to drive from Salt Lake to Moab, and do trails in Moab first, get the feel for sandstone, and then go out to Hole in the Rock. 2-3 days in Moab is pretty fun. In fact Hell's Revenge one day, followed by Golden Spike the next, and you would be all schooled and tuned up for HitR. After HitR, directly back to SLC. That would use up your 8 days.
Sorry this got long winded, but it's a great place. I usually try and spend 2 weeks at a time there, there is so much to do.