You can rob a bank, an armored car, a store and even make and sell drugs! There is a nice amount of variety and I know in my case, I never ended up having to two do heists that were exactly the same back to back. One of the things that I really like about Payday 2 is how there are many different kinds of heists for you to do. There are plenty of difficulty levels and the higher the difficulty level the more you are rewarded so there is a lot of incentive to replay heists on higher difficulty levels.
The game does give you a few breadcrumbs to help you get a bit more invested, but I do wish that they could have given us a proper story to enjoy.