30th Birthday Party ideas?
Salt and Peppy
Start with her best friend. Put her in charge of the guest list. Tell her how many guests you want, and she can get it done. Her parents are a must. And maybe your parents, too, if she is close with them. Then, maybe 10 or 15 friends and coworkers. Don't go crazy. I wouldn't invite any out-of-state friends or family. 30 is not a huge milestone birthday, and they'll just feel guilty for not coming. Secondly, if your apartment is large enough for 25 or so people, then definitely have the party there, where your girlfriend is comfortable. But if you can't accommodate that many people, a room in a restaurant is perfectly acceptable.
Mandy
It depends on what kind of celebratory scene your girlfriend likes. If she likes to go out to bars or clubs, I would rent a space at her favorite location and invite her closest friends. If she is close with the out of state friends and family, and the event would be worthy of them coming into town, it is worth an invite. Especially if the party is a surprise and she doesn't get to see them much. It will add that much more excitement and enjoyment to see people she loves but cant visit often. If she likes something more low-key, I would stick with the in state friends and do something at home or at a local restaurant. It can still be a surprise, but not really worthy of a far travel for out of town guests.