which is more personal?

If a girl runs into you, chats you up, hints at where you can find her; then when you ask her what she'll be doing after she says she's busy and asks if you have a facebook what would you do?

Should I try to get her phone number or just give her facebook info?

It's always a good idea to go for her number but sometimes girls aren't willing to give it out to random guys. If she gives you any sort of contact info tho, take it as an IOI as she could very easily not give you anything. If she asks/hints at where you can be reached, that is an IOI as she could just say: "well, it was nice meeting you" and then you never see her again.

If she asks me about FB I'll say "I have one but against my will so I don really check it. So it's probably better to give me your phone number if____" I then insert some sort of joke that relates to our conversation so the last thing she thinks about when deciding whether or not to give me her number, is laughter and joy. Think about it. It's more likely you'll get her number if you make her laugh as opposed to making a simple statement.
I often tell girls that I'm a better dancer than they are or I tell them I wanna teach them some good moves so I'll say "..... so it's probably better if you give me your number so I can show you up on the dancefloor ; )"