Call me weird but the one thing I really want is an in game capability to change shoes on my Sim. Just the shoes separate from the outfit.
I hear you Petunia! I scream from the "roof tops" of mts2 irc chat about that.. a lot. XD Shoes are one of the biggest pet peeves I have from both EA Maxis and custom content creators. So many downloads I have to change (sometimes moving the texture onto a new mesh!) to have suitable shoes.
As for new expansion pack ideas.. I want apartments. I want old folks' homes! I want mental wards!