I think I must be pretty lucky. I get along wonderfully with my in-laws. In fact, we lived next door to them for the first 2 years of our marriage. (Just happened to work out that while we were looking for a place to rent until we bought a house, the home next door to them became available and it was a deal we couldn't turn down.)
Had a lot of people tell me "Are you crazy? How could you even think about living next door to your in-laws?" But you know what? There was never a problem with living next door to them - not a single one. I'm not saying that I've never had any differences of opinion with them, but they've been normal disagreements that you might have with anyone you know. Not something that turned into a grudge-match, horrible in-law incident.
We moved into our own home a few years ago, but the in-laws still live under 15 minutes from us. It actually is convenient, because we have quick access to babysitting when necessary.
