B.F.
We bought a play structure 5 years ago from Rainbow. We've since moved it twice, by Rainbow. We've had it resealed by Rainbow 2 times, (with each move). It is very solidly constructed, though it is starting to show some wear and tear. My kids play on it at least 5 days a week. I don't see any reason why it wouldn't last another 5 years.
Rainbow is nice because you can start with a basic system and add to it as your boys grow.