I have talked with another mom about twice a month meetings: one week doing coffee and one week doing lunch. So far, we have not organized anything official, but have done coffee a few times, lunch once and a movie once. We also had an after-school outing with the kids.
Date nights are also something that can be scheduled to make sure you have your own time. If finances are tight, you can arrange a routine trade-off with a friend so that you each get a date night once a month and once a month you watch the friend’s child(ren).
Another option is to look for places that have a regular kids' night out event. Plan to take advantage of those when they are offered to have your regular date night. I have seen them offered at gymnastics centers, inflatable bounce places and my daughter’s school.