I use a Kelty Gunnison 2 tent that has good room, vestible on two sides (it has two doors), and is under 5 pounds. I paid $120 for it, but I see it is more expensive this year. Similar tents, but with only 1 door, are these (note most under 5 pounds):
Kelty Teton 2 $120
http://www.rei.com/product/747994 (see reviews)
http://www.campmor.com/webapp/wcs/st...Id=40000000226
Kelty Grand Mesa 2 $110
http://www.campmor.com/webapp/wcs/st...Id=40000000226
Kelty Gunnison 2 (do search for prices, some can be found under $130--has two doors which is nice feature other tents here may not have)
REI Sierra Dome 2 $100
http://www.rei.com/REI-Outlet/product/750075
REI Camp Done 2 $100
http://www.rei.com/product/731378 (excellent reviews; no vestibule)