If you want something really lightweight and roomy, you might consider a tarp tent. A tarp tent made from SilNylon combined with a mesh inner bug tent is very roomy, has excellent ventillation, weighs about 2.5 lbs with stakes, and packs into a very small volume. You can suspend the tent between two trees, use downed limbs as tent poles, or take a pair of trekking poles for supports.

I've been using a homemade tarp tent for two years and it makes a great three season tent. It is a bit out of the ordinary, so it's not for everyone. But they do work very well.