There are really two different classes of vehicles with 3rd rows. Some are large SUVs - where the 3rd row is substantial in space but the vehicle is also substantial. Ford Expedition, Lincoln Nav, Toyota Sequia, Chevy Suburban Nissan Armada, etc all fall into that. I decided it was just too big for me. Then you have slightly smaller SUVs/Crossovers with a token 3rd row. Large enough for 2 children, or small adults, but not really practical for cross country trips with people in the back. Plus the 3rd row takes up the majority of the storage space behind the backseat. Toyota Highlander, Honda Pilot, Kia Sorento, older Hyundai Santa Fe, Hyundai Veracruz, Ford Explorer, Chevy Traverse, Mazda CX9, Suburu Tribeca, etc.
I opted for one from the second list. The 3rd row would rarely be used and I needed better gas mileage and a smaller car since the majority of the time, it's just me. I bought a Mazda CX9 - used (2007) and LOVE it. Can't tell you how well it suits our lifestyle. It's built on a Ford Edge platform and drives like a car. It was also an affordable price point for us and has a good CR reliability record. I recently folded down both rows (which lay flat) and got an amazing amt of stuff in the back. I've also taken 6 adults for a drive in and everyone was comfortable.
We started our search at the car show, since I could sit in and mess around with just about every car out there in one hour (with no pesky salespeople!). Might be worth your time to visit one if they come near you anytime soon.