Facebook is actually a very good idea, yeah. Even if you yourself don't use it much, you'll make it very accessible for others to see and get interested. Sometimes you'll get a way bigger community discussion there than on the actual forums. Another one is Twitter. While the average smasher is still slow on having an account, it doesn't hurt to have one. Then you can have it on your stream to help advertise. Basically social media is a must. I feel like you should've started advertising your tourney way earlier, but it's too late now.
As for the tourney, retaining players is a big thing. I used to be part of the Utah scene and well... let's just say Utah wasn't the most accommodating scene. Keep an eye out on what's going on in the room. Try to not make it like they're there only for their matches, talk to them. Going 0-2 and leaving without interacting with people isn't going to bring them back. If they have a pleasant experience, they'll bring others back with them.