Having seen a some of Boise itself last year, this year I decided to go a little early and try to see more of the area. What popped up as I searched for possibilities was Craters of the Moon National Monument. Lots of geology, and a type (volcanics) that I've seen very little of. I've talked my friend Krissi into coming early, too and joining the expedition.
Unfortunately, the weather looks to be extremely hot (100+, maybe), so we want to be there early, do some walking and some photography, and then get back into air conditioning. The general plan is: I fly out Friday, and will do other sightseeing 'round and about. Krissi comes in Saturday afternoon. I'll pick her up at the airport and we'll drive to Twin Falls, ID--under 2 hours from Boise. We'll spend the night there (and look around, as there are 2 sets of twin falls in Twin Falls, plus the Snake River canyon itself), get up early, and drive to Craters. That looks to be another "under 2 hours" drive. We'll see what we want, then dilly-dally our way back to Boise either by following the Snake River and looking for sights of interest, or by going over the Sawtooth Mountains (probably too ambitious both for my driving comfort and the time we have). I just have to be back with time to swap the car from a personal rental to a government one to start my official travel Sunday evening.