The Big Bertha bags, very roomy. The other thing you might want to check out, since I used to get the claustrophobic feeling too - is what is known as a sleeping bag liner... meant to preserve the more expensive ultralight bags, the liners are made out of a variety of things, like polypropolene and silk, you just slide around in the liner with no catching your feet on anything.

I wouldn't think of NOT using a liner anymore, it's just very comfy and slick.