My sons aren't jelly eaters either. Most of the places serve Uncrustables. However, we've been able to get PB without jelly at the Riverbelle Terrace. They serve Mickey-shaped PBJ sandwiches and (at least in 2007) you could order them without jelly.
I usually carry Jif Singles in my bag and just order plain bread or a plain hamburger bun to spread it on.