sounds like a tough one
gear is a back and forth battle. you want lightweight and lots of headroom. thats a tough order.
i would try to broaden your ideas on a shelter. check out
www.hennessyhammocks.com
there are other hammocks but that is a good place to start.
you may not be able to squeeze a sitting up position but the absolute comfort you feel is remarkable. in my opinion the value of the hammock exceeds any tent. I am coming from the perspective of a long distance hiker tho. i used to use a sierra designs clip flashlight cd. now its nothing but a hammock for me.
basically:
what type of camping are you mostly doing? car camping or backpacking?
are you looking for a solo shelter or something to snuggle up with someone in?
have you ever thought to yourself "i wish the ground was softer?"
what do you want the shelter for? planning on some card games or a place to rest after a long days hike?
for me:
i want a solo shelter that will be of high value in regards to weight, comfort, and $ value. what i chose was the hennessy ultralight backpacker asym. weighs in at 1.9 lbs. it is the most comfortable gear i have ever owned. it absolutely beats any form of ground camping. no pressure points, no aches. cost me 129.95 (they make a model for $69 i believe) oh yeah, throw away any previous notion of what you think a hammock is like. its not a banana sleep, nor a shrimp sleep.