Been with ktspktsp for going on 11 months now, and whenever we're around each other with any regularity (e.g. when we lived together for 5 months before he got a job), we had sex pretty much every night. It probably averaged out to 5-6 times a week. Now that we are three hours apart and only see each other on weekends, we still average about 5 times a week!!
But I guess this will decrease over time, as it seems that most long-term couples (married or not) experience this phenomenon. I enjoy all the sex that we do have right now, but I understand that with increasing obligations of work and/or family, we'll have to limit ourselves as time goes on.
I have a question for all you married folks, though: how often do you have quickies? ktsptktsp and I find that we can have pretty good sex in the span of a few minutes sometimes, which keeps us going when things are busy... but maybe this isn't practical with a family?