I (the mr) go out on "dates", although for us, one of the reasons we also play separate is babysitting. So when one of us is out, the other is at home with the kids in some fashion (kids are in bed already or possibly out somewhere).
We do have some friends who both go out on concurrent yet separate dates. They have older kids though, so it's not such a score for them to get babysitting. For us, if we manage to get babysitting, we are going out together. We save the separate stuff for times when that isnt the case.
Back to topic, typically what I do is the normal nighttime routine with kids. Dinner, homework, bedtime routine. Then I do my typical nighttime routine, computer time, tv, go to bed. She normally doesn't go out for that long (unless she's out dancing) so I don't fall asleep before she comes home.
Normally when I'm out, it's later in the evening, so the kids are already in bed, and she just does her normal evening routine.
In either case, we wake each other when we get home (if the other is sleeping) and enjoy ourselves some more. Followed by more fun the next morning.