Hi Dana,
A good idea for your man is to organise a night out with his friends every fortnight or three weeks. It might not seem alot if you guys used to be out all the time, but the fact is, once bub is born, he'll be going out even less. May as well ween him out of it!! Also if it's planned, you can prepare something to do (even if it's just dvd or catch up with girlfriends) and he won't feel guilty and neither will you.
Another idea is to meet friends for a barbie in the day, or have people to your house in the day . There's nothing worse than people partying on when you're so tired at night.
It is a totally different life to the partying lifestyle. With DD, I got pregnant in UK which is where I was for 2 years pretty much to party. So I came back to a different world, I couldn't party at all and it took time to adjust. I found that doing things with my mum actually helped, and going with her to family friends. That way I was around older people (my friends were all still partying). This time around we are older (ok 31 is not soooo old, but we can't stay up past 8.30pm, it's ridiculous)!! But we do alot of family things. Lunch and dinner at my mums, sisters or inlaws. It's really nice, and they love talking about the baby which is great (friends are never as excited as you about your baby)!!!
We also go to the beach for walks, watch lots of dvd's, have naps (!!!) and go out when we can afford it to breakfast/lunch/dinner. We are loving it, we get to spend quality time together and talk about baby.
Good luck and enjoy your pregnancy! xoxo