Your invitation will set the stage for your evening and build anticipation for your guests. I've come up with sample invitations for each type of affair.
Broadway Nights - I'm thinking a little more formal, possibly black tie. The black and white of the invitation would be echoed in the table decor. I'd keep it formal, but simple like the invitation.
Sex and the City - Similar to the Broadway Nights, this is a sort of formal Girls Night Out. Black and white with accents of pink, and lots of glitz and glam.
Carribbean Getaway - Think Key West, Jimmy Buffett, Pina Coladas, and lots of beachy pastels.
Mexican Fiesta - I wanted informality and bright colors to complement spicy, flavorful, casual food.
Girls Night Out - I have a much more casual girls night out in mind for this one... good friend, games and wine.