Kathy, we went through it 4 times and they are all older than 21 now. They grow up. One thing that they don't teach in parent school is that you want to think a little down the road with kids. The cowboy decor they loved at 8 will be out of date by 10 and totally uncool by 13. The only good thing is that they pretty much quit talking to adults about that time anyway, you if you hear this it will be indirectly. It's the same with swing sets, sand boxes and a lot of similar items. You do have to change with them.
I am NOT saying not to build them toys and storage space. But if you can think ahead and consider future uses and space, you will be ahead of the game. There are some really neat roll-around storage areas available and more stores with more ideas now than there ever have been. Your situation will be yours and a shopping trip to see what the other person involved thinks, followed by ice cream, is generally a good idea.