I've seen Capoeira in action which is a very specialised dance / martial arts style, I realise the Brazilians call it a 'martial art' but to be honest with you I don't believe it to be an effective style of fighting, too many fancy movements and way to complex to learn as it requires very precise movements.
I don't wish to disrespect you in anyway but I don't see many people going for this kind of style although there are people who do it, most of the competition is from MMA (UFC, Pride, Cage Rage etc...), Muay Thai, Karate etc... Most people who start to learn martial arts want something fairly simple at first such as boxing just to get fit. I've been training in the martial arts all of my life and stick to styles such as Judo, Brazilian jujitsu and Thai Boxing.
I believe your best bet would be to target children with lots of energy and not advertise it as a 'martial art', advertise it as a specialised brazilian dance system that is excellent for staying in shape (which it is

), you will get lots of interest from, as I stated children, perhaps women who want to have lots of fun with their friends on an evening, you probably will get men joining for toning purposes etc... In all honesty I don't see someone joining to learn to 'fight' or defend themselves from an attacker.
just my 2 cents!