A store near my house is having a great sale on athletic clothing and I tried some compression shirts on yesterday. I actually didn't realize they were compression style clothing until I had them on.

I tried on my "normal" size which is a Large and it really seemed comfortably snug. Actually I hadn't looked that good in a while either

I wasn't really sure if they were supposed to be that tight so I went up a size (XL) and while it fit snugly in the chest, torso, shoulders and forearms, it was loose(r) around my upper arms and towards my waist. In fact, the Large really made my abdominal area (love-handles most noticeably) a lot more contained while the XL left my waist-line in it's more apparent "birthday suit" form.

I've done some other research and understand the thoughts behind the benefit of compression clothing. This was a good article:
Speed Training: Compression Clothing

It seems to me that the "support and containment" aspect of the clothing is one of its main benefits so if I decide to get some should I go with the smaller or larger clothing? I'm thinking smaller...

Go smaller. The thing with compression shorts/tights is they will feel very tight in the waist. Ditto for the tops.

They should feel comfortable, but tight. And yes, any fat you have will be pushed up from the hips and down from the upper body. If you don't have a muffin top in compression wear, you're in pretty good shape

LOL! Thanks. I ended up going smaller mainly because I got the same impression you posted from the article I posted.

Yeah I would go smaller. As I play rugby and it's a winter sport i have to wear these and the whole point of them is to feel tight but snug. If it's so tight you're having trouble breathing then go up a size. But that rarely happens and as you said the sizes both feel snug. Arms don't matter to much, it's the torso that has to be snug.