Our average evening or weekend morning sex is between 1.5 and 3 hours. We have a series of weekday quickies, (usually between 20 45 minutes) daily then follow those up nightly marathons, occasionally skipping a day due to fatigue!
Yeah, when our kids were younger, we had more quickies, but I used to be able to have an orgasm in like, 5 minutes, and certainly didn't want sex every day or twice a day back then. When the kids are a little older and either sleep on their own or our out on their own you have more time for marathons.
It takes me a lot longer to come than it used to, but now we really investigate all our sexual options instead of "Hurry up! I hear the baby stirring, COME g'damn it!"