I 2nd Under the Nile fitteds. My 2-mo-old is wearing one right now, under an Aristocrats wool cover.
I agree that Luke's Drawers are too bulky. My 2-year-old refuses to wear them! He actually uses disposables at night, because no matter what I tried he would still wake up crying a couple of times a night. We did try using a BumGenius at night for a little while, and if I remember correctly, he didn't leak. I'm loving Haute Pockets now. I think they would work at night if properly stuffed.