Wendy I love going in summer, and go almost every year in either July or August. This year I went in late May into June,, and I did NOT find it less crowded ,, so really there is not that much wrong with July August,, as long as you get a hotel with AC,, my one must.
I also find, if you book hotel early, by say , March April,, that many hotels have price breaks from mid July thru August. I paid more for my stay this year then I wanted too,, and I had originally thought I was going in July, so had already a cheaper rate booked( but had to cancel)
My other tip is,, allow enough time,, yes, there will be some crowds and lines, but really why stress about it.. the ones that seem to are the ones with "three days to see Paris" and long wish lists. Take as much time as you can, so you can just relax and go with the flow.