Actually right now is the best time to go because all the tourist are at the valley floor area. I am up there at least 2 to 3 times a week and the place you want to hike is the glacier point area. Now not the tourist glacier point but the hikes around the area.

The traffic is low as most people do not want to hike more than a mile. Also hit Tioga pass. You can get some stellar images but you have to walk. This is the best time to go as 90% of the tourists head to the valley while the locals hit the high sierras and upper elevations.

Also do not forget the Sonora pass. Really beautiful and there are some really nice hikes along that route as well. You could take Sonora pass down to 395(I think that is it) then head over to mono lake and bodie then back through Tioga pass via Yosemite! It is beautiful.