I'm glad you pronounce it like layf :)
Personally I think it's a bit dated and it would be strange to meet a young Leif but that's just me.
Most of your combos are very nice. I especialy like Leif Alexander (great combo and I love Alexander as a middle name) and Leif Alistair.
Oh and I know a man named Leif too, his wife is Leila and their children are Leo and Laura... (and they had a dog named Laban and a horse named Lappi)