I like layouts with either cool or soft/pastel colour schemes. Big fan of boxes too, for some reason, so long as they follow a grid pattern and are aligned and stuff. (Basic Boxes and Stepping Stones make me twitch a little.)

Also I thought I might add that I kind of rely heavily on Friends/Circle colours (it's just faster than looking at usernames), so I've been avoiding changing layouts because I'm never really sure if it's something layout makers take into account and worry it'll mess up the whole look.