I think some people need to realize that there isn't only one camping method that is perfect. I've used all kinds of tents and each has its own positives and negatives. At the risk of inciting another tirade I think it's pointless to judge gear by what is sold at REI. If you followed the advice of the REI salesman you would easily have 25-40 lbs of gear for a camping trip. That might be fine for the majority of people that limit their backpacking to a couple of miles but I definitely prefer to backpack in the 12-15 lb range.
As far as the original post I think he needs to be looking for a 3 person tent if he is tall and wants some extra room. I have the normal Quarterdome and it is kind of small inside with another person (5'10 and 5'5"). It doesn't bother me but I doubt the longer version is roomier other than the obvious extra length.
I'm setting up for a 2 month tour in Hokkaido next summer and currently an ordinary 8x10 silnylon tarp (1lb) with a bug bivy is my most likely choice. With the bivy and all lines and stakes the total weight is around 1.5 lbs. It's not the perfect shelter though but it's a lot roomier than a tent and offers a lot more ventilation in the summer.
I've also backpacked with these
5'8' poncho tarp - not really an option unless you really don't expect to get any rain. Held up to 12" of snow in a SoCal snowstorm (May 2008) until water was running under everything.
8'10' tarp - pretty awesome and light as long as you have bug protection and at least one high point to tie off to. Does not offer any privacy though if that's important.
tarptent virga 1 person - only 2 lbs but pretty small. The tarp/bivy is lighter and significantly roomier and typically more stable. This is an older model and the new tarptents have improved but I haven't camped in them.
REI Quarterdome and TNF Tadpole - I prefer the Quarterdome because it is lighter and it has two doors on the side. the vestibules are more usable also. I could also take this on my trip because there are more pitching options but it's also almost 3 lbs heavier.