LTCs are not very useful imo, they're just a copy of Bitcoin and their only purpose (well for me) is to trade for Bitcoin.
BTC all the way for me.
Pretty much +1. I bought some LTC recently, but will be selling it off for BTC as soon as Mt.Gox lists it and the price jumps up. To me, Litecoin has no fundamental advantages over Bitcoin and has the significant disadvantage that it does not have the same market penetration that Bitcoin does.