It is much less since we had children but they are still there in the background. Facebook does help stay up to date with them without having to book a babysitter and make a date. Some people think that's sad but at the moment with the children so young and the distance with some of our friends its that or nothing so I can't see it as a bad thing.
We are in a dinner party circuit more locally though, a group of 5 couples who are all friends with each other, so 10 in all, so when its your turn you cook for 10 which is scary - but we take it in turns every 2 or 3 months and those nights are fantastic and much anticipated within the group.
I see these people week to week as well, those who dont work, as we have children the same age.
We have more distant friends we catch up with about twice a year, several sets of these, and we tend to see them once in the spring/summer and once before Christmas, basically we take in turns. These tend to be weekend get togethers at one or others houses, as once again, most have children these days.
These are various people from various jobs schools unis etc that you keep being friends with, who's weddings you were going to 10 years ago and who's kids you have seen being born (not literally but you know what I mean)
But the big long nights out in London are pretty few and far between these days, but that's okay. I could have them if I really wanted to.