The section of the Last Chance Trail from about Jackson Falls area to Last Chance Camp is pretty bad. Last time I tried to hike it (about 5 or 6 years ago), the trail just seemed to vanish at some point into thick brush. There was no more indication of it… just gone. I haven't been back since to try it again, although I'm tempted to.
I heard a second-hand report that a friend of a friend hiked some of this a couple of weeks ago on a day hike. I was told the trail conditions are pretty awful up past Jackson Falls. Not sure whether the reporting hiker was able to make it farther up or not.
The biggest hang-up, like Rob said, is the break-in problem at the TH. For a day hike, the risk probably isn't that bad, but leaving your car there overnight seems like an invitation to trouble.
If you guys decide to team up for a hike, let me know. Depending on when, perhaps I could join along. Or at the very least, give you some ideas for a couple of trips. There's some opportunities for some fun adventures with scenery sorta' like the Punchbowls…