I bought admittance to the musuem and the tower. I did get a small discounted for purchasing them together. They told me the ticket allowed as many in/outs as i wanted in a day and also was good for the following day. You don't have to see everyone in 1 marathon session.
There are 3 options for 3 parts of the museum, or you can get a full access pass to see everything. The full access is the best deal if you have more than 3 hours to spend there. You have to call the office to get a group rate.
You would really need to contact the website or museum by phone for a more definitive answer.
There was no combination price for a small group that I know of. We paid in full for my wife and I. Also do not know if there is a large group combo price. They do have discounted prices for seniors, veterans, and children.
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