Here is a good reference point as to what tangs are appropriate for what tank sizes.
http://archive.reefcentral.com/forum...hreadid=739380
There are some great fish that you can keep in a 65 gallon tank. You could get a pair of clowns, a dwarf angel (some nip at certain corals), a goby, a blenny, a hawkfish(will eat ornamental shrimp). There is alot to choose from. If you want to keep tangs I would do alot of research on them, and then set up a tank that is appropriate for their size, and that can handle the bio load they add to a tank.
While your setting up your new tank make a list of fish you would like to have then research them, and make sure they are compatible with your set up.