The Jets and Gaints are sold out. You might be able to buy some tickets on the internet from a sane season ticket holder. I've been to a Pats/Jets game at the Meadowlands (the comback in 2001, it was hilarious!!!) and the Meadowlands is a nice place to watch a game.
I would highly doubt that you could get any tickets for the Cowboys.
The Ravens might be out of it by week 13, so there is a chance.
But your best bet seems to be the October game in Miami, good time to be in Miami, and you should be able to buy tickets from the team.