The things high on our list when shopping:
- No front cabover window (to avoid the leak issue) We do have side windows, which like DrewE said, are great for ventilation up there. Not sure of the age of your kiddos, but our DS is now 11 and has never been able to do more than pop his head out, they're just too small for him to fit through...if that's your worry.
- Fiberglass roof
- No signs of water damage (as it turns out there was some we missed at the rear window, which turned out to be the upper cyclops brake light...but we got it all dried out and sealed up now)
- Floorplan and space for what we wanted. Our TT was fairly small and didn't have a sofa, that was on our wish list for our C so we would be more comfortable sitting out rainstorms and such. Think about what you wish your TT had or didn't have. What part of your TT floorplan works for you, what would you do differently, that type of thing.
- And then of course the chassis, like Jaycocreek mentioned. You want to make sure the engine is in good shape. Be wary of older units with low mileage. That seems like a creampuff in the car world, but in the RV world that means it has been sitting somewhere for a while and the engine has not been exercised which might cause problems.
- Oh, and tires, be sure to check the age of the tires. If you're not familiar with the date codes on tires, Google how to read it and make sure the tires are recent or plan to buy a new set of 7 (including a new spare)
Happy shopping! We love our C and are very happy with our decision to trade our truck and TT for it.