The Tube is not free-to-distribute. I have approached them for broadcast rights on cable, and they are very much an "over-the-air only" service. The person I talked to (I cant think of the name at the moment, but he was one of the Vice Presidents) conceeded that this position will probably change in the future, but as of right now, no cable system is allowed to have them
The only channels you are going to have an easy time with, are local OTA networks, anything satellite delivered is going to have licensing fees associated with it, unless they are very specifically "Free-to-distribute".. The only one that comes to mind is C-SPAN. That channel is specifically a Cable-centric channel, and is available on AMC 11 C-band analog. It was originally designed as a Cable only news channel, but so much for that idea..
Is this a municipal cable system? or perhaps a housing development? You may want to check with your local government and the FCC for must-carry rules. If this is for a franchise, the Franchise agreements would stipulate any channels that must be carried.