Hi. Doing some logistical planning for a summer trip. Can someone give me an idea of the usual summer condition of the Trail Creek Forest Service Road from Sun Valley over to US 93? e.g. - Is this 35 mph graded gravel, 10-15 mph rocks and potholes, or 4WD? Thanks much!

35 mph graded gravel, but you can drive 50 mph most of the time. the road is frequently traveled.

You don't need 4WD-- you can drive any type of car on it- and yes, a bit rocky and potholed in sections. Note that it is closed during the winter and into the spring because they don't plow it.
If you need local info for your climbs, here's a (searchable) local discussion group:
http://www.network54.com/Forum/105717/

Please note the road is notorious for teaching folks how to find their spare tire. I would make sure you have a full-size spare (not a donut), and make sure it is in good condition. The Les Schwab Tire Center in Hailey or Idaho Falls (depending on your approach) will be happy to set you up properly.