Haven't been this year (heading down at the end of May) but have been down several times the last being fall of 2011. It's a great river for kids/beginners. The first 20(ish) miles are pretty slow but then begins to pick up. Consider scouting Steer Ridge, Joe Hutch **, Wire Fence& 3 Fords (can scout Wire Fence & 3 Fords at the same time, stop on right above WF and walk down to 3 Fords). Can read & run Wire Fence then pull in below Wife Fence and walk down to 3 Fords-there is a good vantage point above the rapid on the right.
Lastly, consider scouting Coal Creek, just suggestions but my first trip I scouted the rapids listed.
**A few years back a flash flood deposited new rocks into Joe Hutch Canyon (the second of the two Joe Hutch rapids, the first JH Creek is a read and run rapid). The rocks constricted the water towards the left (can run the right side at higher flows). There is a distinct tongue on the left side-scout your line and watch out for rocks on the far left towards the end of the rapid.
This guide is good and has accurate listings for some petroglyph areas.
Amazon.com: Green River in Desolation & Gray Canyons: Sports & Outdoors
River Runners Transport (out of Vernal) are great for shuttle service.
Have a wonderful trip, maybe we'll see you out there!