Njgal - How about being creative. If the inlaws are going to stay with you, how about buying a place where they occupy mostly the top floor? Or how about buying two separate condos next to eachother? Problems can be minimized if everyone has their own space.
Stork - you are right. Space helps. Plus I don't mind sharing space.
My point is you are bound to hear opinions about your lifestyle choices. I think you have to mature enough to hear them, evaluate them and decide whether you want to act on them.