+1 on the Doublenest. I've had one for a long time and have done a lot of camping with it. It's big and comfy, but packs small.
My advice to you: if you're planning on doing some hammock camping and want everything to pack small (and light), bite the bullet and spend the money on a nice down under quilt and top quilt. Messing with a sleeping pad as bottom insulation is a pain. It's much nicer to hang in a hammock that's surrounded by warm, soft, down! And using a sleeping bag as top insulation works well, but you're packing a lot bulk and weight you don't really need. A down top quilt packs much smaller and is much lighter than a similarly-rated sleeping bag. I have a Zeppelin under quilt from Underground Quilts and a Sierra Sniveler top quilt from Jacks-R-Better. I bought the under quilt first and continued to use a sleeping bag as top insulation until I had the money to spend on the top quilt. Now, I'm really happy with my hammock system. (I'm currently waiting for a new Warbonnet Blackbird XLC hammock that I have on order.)
Head on over to Hammockforums.com for tons of info on hammocking from a bunch of really nice folks. It's a great forum!
Stay sharp,
desmobob