I think that the addition of rental prp's could be fun. Have various levels of property from rent spare room/basement to rental complex. A unique thing about a rental is that the land/building value increases while the renters also pay out rent to the player. I think that, due to being a rental, the value should increace slower than a non-rental property, but you get the added benifit of revenue as long as you own the property...more or less like real life. Additionally, it would be nice if some new property types could be introduced...maybe i'll try to think up some other types that could be added and help fill out the middle.