I've got a big agnes Seedhouse SL-1 (1 man tent). Fits me ok but might not be long enough for someone tall. Quality is good and weights just 2 pounds. I probably wouldn't buy this model again though because the entry is at the end and can be a pain to get in/out of. Would definitely get a tent with a side entry next time. This would probably give it a more stable profile as well. Mine is very narrow so it can get whipped around like crazy in the wind.
Next time I'll probably take a weight penalty for a 2 man tent and get something that will stand up to wind a bit better and have a bit more room. Lots of great brands out there.
I have an OR Alpine bivy too, which has been awesome, 2 pounds as well. I actually use it a lot for car camping since its so easy to roll the whole setup up and throw it in the back seat when its time to move camp. I don't take it on trips where there is decent chance of foul weather as it would not be fun to have to hole up in a bivy to wait out the rain.
I don't think I'd ever get into using a hammock. Not comfy for me to sleep in, and not enough trees down here!
+1 on the tyvek ground sheet. Go to any store that sells lumber and get one of the sheets the lumber comes wrapped in. Light, tough, and free!