I am pretty much with Jantango here - tango (and milonga and vals) exists only at the milonga, in the music.
If you are going to milongas, and feel comfortable with the way your dance fits the music during the tango tandas, but when you dance the milonga and vals tanda you are unsatisfied with your musicality then doing extra classes in milonga and vals will probably help.
If you are as happy/unhappy with how your tango feels, and how it feels when you "fake" milonga and vals by dancing them "flat" (i.e. without picking up the vals waltzing or the milonga swinging - which is actually perfectly fine, and i often think more people should throw in a few moments of flat dancing into their dance and explore the other rhythms in vals and milonga besides the obvious ones), then more social dancing and listening to the music, and working on the mechanics of tango in tango classes gives you probably more bang for your buck.
Another thought - this also depends on how you are dancing - i personally at the moment prefer a parallel close embrace with some weight sharing. And i keep this preference in tango, milonga, and vals. I see quite a few people who dance different embraces in the different styles - e.g like JohnEm seems to do - in that case your perspective might be very different from mine.
Gssh
If you are going to milongas, and feel comfortable with the way your dance fits the music during the tango tandas, but when you dance the milonga and vals tanda you are unsatisfied with your musicality then doing extra classes in milonga and vals will probably help.
If you are as happy/unhappy with how your tango feels, and how it feels when you "fake" milonga and vals by dancing them "flat" (i.e. without picking up the vals waltzing or the milonga swinging - which is actually perfectly fine, and i often think more people should throw in a few moments of flat dancing into their dance and explore the other rhythms in vals and milonga besides the obvious ones), then more social dancing and listening to the music, and working on the mechanics of tango in tango classes gives you probably more bang for your buck.
Another thought - this also depends on how you are dancing - i personally at the moment prefer a parallel close embrace with some weight sharing. And i keep this preference in tango, milonga, and vals. I see quite a few people who dance different embraces in the different styles - e.g like JohnEm seems to do - in that case your perspective might be very different from mine.
Gssh