I have a 97 T-100 and had a 05 Tundra, both 4wd and both ex-cab. I know you asked about 2wd but thought I might be of a little help with a comparison. The T gets 20mpg with the 3.4 v6 and the Tundra 18 with the v-8. Both using Mobil 1 and I am easy on the gas peddle. Loaded with my pop-up camper they got about the same mileage, about 14. The tundra has a lot more power and reserve when loaded. As far as room in the back seat, the T has a little more because the tundra seats are more plush (thicker) and comfortable but at a price of less room. The backs on both are pretty much straight up.
The rear doors on the tundra are a godsend for kids but you still are not going to gain space if that is the true reason for the upgrade.
The tundra is a lot smoother and comfortable to drive but I love my T also.
I traded the tundra for a Corolla for the mileage and kept the T for work. I do miss driving the tundra!!