If you are producing large numbers, wheels are a HUGE mistake. I say this because they are a major pain to keep up with, and very expensive because they will litterally wear them out making you have to buy more.

My experiences have shown they are also much more interested in the wheel then the kids.

If they have the wheels and then you remove them all hell will break loose. they will be mad at you and in my experiences will kill babies and constantly slam the water bottles against the glass.