This year we got the kids one big gift, a 15 foot trampoline. It's huge. I had planned to assemble the thing in our garage, but it was way too big for that. It took 2 hours to put together and required the help of a couple guys in the neighborhood.
Perhaps the biggest challenge was our yard: It slopes downhill. We had to dig out a couple spots to level the trampoline. But it's a blast. And a good workout, too!