I bought my full size crew can F150 at the end of 2012. I previously had a small truck and it was useful for a variety of projects around the house(kitchen remodel, landscaping, etc) and with a 4 cylinder I still got over 20mpg in the city which was on par with the cars I was driving before it.
Unfortunately I needed a back seat as Baby 2 was in the works. The utility of the truck bed is still nice on occasion(has half a load of dirt for the garden in it ATM), but may not entirely be necessary. We are also working on Baby 3 right now, and the beauty of the big truck is that the rear seat has 65" of hip room. With "narrow" carseats coming in at 17" I shouldn't have a problem fitting 3 across. However, I spoiled myself and got a "nice" truck, though none of the supercrew cabs are inexpensive. I went from a ~5000 truck to a $26,000 F150 Lariat with an Ecoboost engine rated at 16/22. Unfortunately I mostly do city driving and I have found that 16 to be closer to 13-14 mpg.
In looking for an alternative vehicle, I am reluctantly willing to give up my truck bed. However I do still anticipate needing to fit in 3 car seats starting next year. I was eyeing a wagon/crossover or sedan, but most are about 55" wide, which may theoretically allow for the third seat but in reality may be too tight. We almost got my wife a Ford Taurus in lieu of the van she ended up with and at least with the seats we had at the time we struggled to get three in one row. I got a great deal on the truck, buying it from an out of state dealer. I paid $26k and it appears that I may be able to get the full 26 back out of it. I think partly because of the good deal I got the first time and partly because of a low current supply as Ford retools for the new aluminum trucks coming out.
A minivan would solve the problem, but not going to have the best mpg, and we have one in the family already.
I could save money and stay Truck-ey but getting an older truck with fewer options(leather)
I could find a compromise sedan/car, would be tight on space but we have the minivan for that. I saw some VW Jetta TDI wagons for not too much, but I think they might be too small. We previously have owned a Pontiac Vibe/Toy Matrix, but they are based on the Corolla and I think too narrow.