Twin beds rock: http://www.divinecaroline.
The wife and I use two twin beds pushed together (which makes a king). So we have independent suspension (and memory foam toppers, oh yeah!) But most importantly: we use different covers, because she likes 3 feet of lead-based quilts and comforters, and I get sweaty head just *thinking* about all that insulation. The bedmate irritation is much minimized by those two things.
The new big thing affecting our sleep: we just adopted a new cat, and she weighs about as much as a VW Beetle, and she thinks that the middle of the night is the purrfect time to walk all over the hoomans and get some attention. Since she's new, and rarely comes out from under the bed (as she has not, as we say, fully integrated into the current feline power structure), we put up with it, but she does that thing that cats do where they concentrate all of their weight on the tips of their paws and just. stand. on. you. When she lays down it's great, it's as comforting as those lead vests you get to wear at the dentist, but she rarely lays down, just walks laps around the bed, up and over the humans, stopping to deliver pressure point attacks. She also head-butts us to get attention, and she's very strong, so it's like, well, being struck by a VW Beetle.