I've seen a reference which stated that basically any starship class with a discrete saucer section should be able to separate.
The Constitution Class was designed so that the saucer could separate from the rest of the ship in an emergency. However, re-integration required shipyard facilities.
The Excelsior (Enterprise-B), Ambassador (Enterprise-C) and Sovereign (Enterprise-E) classes are said to be capable of saucer separation, but this has not been seen "on screen".
The Galaxy class (Enterprise-D) has been seen to separate in several episodes of TNG and in the movie "Generations".
The Prometheus class, seen in one episode of Voyager, separates into three sections.