I find that living with my spouse works best for me because we enjoy one another's company - HOWEVER, to me it is key that I get some alone time, or time with "the girls" because I feel that builds a stronger relationship for my husband and I. I also travel internationally 4 or 5 times a year for 2 weeks at a time - this, while a great experience, also reminds me how much I love spending time with my husband - it makes me miss sleeping in bed next to him... in part because I don't sleep well without him :p. It makes me miss seeing him when he or I get home from work, it makes me miss cooking meals and eating those meals with him. I love my husband dearly and love spending time with him and I know I would never want that to change.
I don't think it's always a bad idea either if spouses choose to live separately because it depends on the type of relationship. My aunt and uncle have two houses. Sometimes they live together in one of their houses, but then they retreat to their separate rooms - this I don't really understand, but it seems to work for them as they've always been that way.
I say, to each his own. It's important to me to have a strong and involved relationship with my husband. It's also important that I get the time I need/want to be alone, to get time with friends, etc. Our relationship has actually gotten much stronger now that we've developed several couple friends - the guys all hang out and talk, the girls all hang out and talk - they intermingle, etc. By the end of the night, we're both happy and feel like we're a part of something bigger than just him and I - it's nice to feel wanted by your spouse, but I find it's also very nice to feel wanted by other people (aka. friends) as well.
