The rooms are now connected! I used a very simple method that's guaranteed to connect and will even create loops to join different "branches" that happen to be near by.
to connect a room:
after placing a room
get a list of all adjacent cells that are in a room
randomly pick some cells to create doors
This can create multiple opening between two rooms. That's not a problem yet but it could be tweaked later on. This should be enough to create the gameplay portion but I'd like to work on defining different regions at the world-gen level before I move on to creating a player to run around.