I have been suggesting this to my friends for some time now! Even to the extent of contriving rides etc, such as moving stair cases, roller coster broom rides or virtual Quidditch matches. It would be a fantastic idea with Hogwarts, Hogsmeade, Diagon alley, Knockturn alley, The ministry of magic, St Mungos and the Burrow, maybe even Godricks Hollow. There are endless possibilities including the Forbidden forrest with all its creatures including Grawp and the knight bus. I could go on for ever, but I'm sure you get the drift and have probably had similar conceptions yourselves.