I am not much help because I wear tight running capris/leggings from Lululemon. Frankly, if anyone's looking that closely at my behind while I'm running, they get what they deserve. I do mostly wear loose shirts though to help with air circulation, and I like them best with a little bit of length so they come at least partway down my backside. I've found tops from Athleta and Lulu, but also good deals on tops from Under Armour and the like from TJ Maxx and Marshalls. The tops are easier to find. I'm way pickier about the pants because so many of them 1) are too short, 2) are wrong in the rise, 3) slide down my waist when I run, or 4) are supremely unflattering. I've tried brands ranging from Under Armour to Champion to Zella, but for me, Lulu's fits have worked the best, and they have a good amount of compression, which I like. Of course, YMMV. In really hot weather, I'll wear looser running shorts, but it's really hard to find the ones I prefer, which have a slightly longer inseam. Too many of them have teeny short inseams, and nobody needs to see *that* much of my cellulite when I run.
Favorite running bras are currently Panache and Chantelle, but I'm a difficult fit and need really good support (32G) so can't wear the cute little strappy numbers they sell at Lulu and Athleta.
Favorite running shoes are Brooks Ghost, but I supinate and need good support under the heel. Favorite socks are Balega -- cushiony and last a long time!
