For us, socialising has really changed since we had kids. I had my first at 36, so we had yeeeears of going out under our belts and don't really miss restaurants, bars and clubs. We're just at a stage where we are happy to socialise together as a family, so lots of meeting up with friends at kid-friendly places, going to each others homes during the day.
We go to our neighbours for a party on a Friday evening every couple of weeks. We drink and dance, the kids run riot, everyone has a blast, then its 12 steps to home at midnight. Every couple of months we have a drinking session with just the ladies in our neighbourhood. Those go on until 3am and everyone's blinds are drawn the next day! Out out to a restaurant or a club, maybe 3 or 4 times a year, if that. With DS1(5) I didn't go out for the first 13 months of his life. I just couldn't bear to leave him. With DS2(10 weeks) I've already been out with the ladies for a couple of hours while DH wore DS2 in a sling. I was right next door though for any emergency feeds (he's EBF). I've got a 40th I am going to next week so DH will have to attempt his first bottle of expressed milk if he wakes! I'll only be 10 mins drive away so I can get back if he won't take one.
I'm happy with the level of socialising we do. Between playdates (either with DS's friends or my friends' children), family events, meeting up with other families and our neighbours, I feel we are never in!