I stated the idea of magic squares because of the practical nature as you really dont need props. Recently Ive been experimenting with bill switches and re-read the Roger Klause $100 bill switch in Ammars ebook edition of Encore 3 (not sure if it is exactly the same as the original Encore 3). Im not sure if this was the original source for the routine but it has seen other mediums besides print before. In fact Ammars Encore 3 is chock full of great routines and not all of them are cards but the card items are great. You can buy this ebook edition as a download from Michael Ammars website www.ammarmagic.com.
Im anticipating this weekend when I pickup the new Switch book by John Lovick from my friend Eds magic shop. The bill switch could be the perfect routine for you to try out and Im sure there are more than enough things to read in the new Switch book to keep you happy for a long time.