Tiffany,
Trust me, the dances they are telling you to go to do not resemble the club scene in any way shape or form. In a club almost no one actually knows how to dance, at dance gatherings there is rarely alcohol and yes there are a few jerks of both sexes but they exist everywhere in every facet of life. You just have to learn to deal with them in a way that helps them understand you aren't interested without doing anything that would make you less of a nice person.
Now....to the question. I actually rarely go to group, but it is only because I am 5 hours round trip from where I dance. I should go and group classes can really add a lot. It gives you a gauge for your progress, an opportunity to practice and build stamina and a chance to build community with fellow dancers. You aren't dancing in a magical bubble filled with happy sunny light that reflects a better dancer than exists. Instructors (mine isn't one of them) can make you feel like you are better than you are and this can keep you from pushing yourself the way you should.
For outside activities, it really depends on you but I just don't see jazz/hip hop helping. They aren't the same at all. If you are planning on going that route, take modern and skip the hip hop. A good modern instructor will help you learn to use your core to develop shapes and drive your movement. The movements in jazz/hip hop don't translate to ballroom at all and only moderatly to rhythm/latin.
Here is what I do.
Flamenco: Helps you to break apart foot and arm movements. Really develops beautiful arm movements and is the basis for Paso Doble so you'll dance this beautifully if you practice in traditional (Iberian) Flamenco.
Belly Dance: Beautiful arm movements and core isolations as well as helping to build movement and flexibility that adds well to Latin.
Argentine Tango: Some will tell you not to do this dance. Don't listen. It creates a stunning ability to follow that will serve you well. I learned it in Argentina and continued classes in America. In the US my instructor was a modern dancer and so this built the framework for my core so it is why I think modern may help.
Ballet: I don't do it, but it can help build arm movements and articulation of the foot which is essential if you want to be a beautiful Latin dancer. Not to mention flexibility and control and core strength.
Core Rhythms: yes it does teach you great core isolations on fundamental Latin movements and flattens your belly so you can wear the Latin costumes with pride.
If you are hearing one thing...hear this...work on your core. You can't be a great dancer if you don't have core strength.
Good luck!
