I like the suggestion of a Stardust-type mission to Enceladus
Titan could be used as a gravity-assist to help send the mission back to Earth. There's precedent for that - 2-3 years ago, here at HZ, Raoul identified a mission that used Earth's moon to escape Earth's orbit (not just to reshape an errant satellite orbit). I don't remember the mission though.
Anyone here remember the Europa Icepick concept? Send an impactor ahead of the flyby, and the impactor knocks up a plume that guarantees you've got something to sample for your flyby. The advantage is that you don't have to drop energy to go into orbit around the primary body. The idea had problems for Europa, apparently, but maybe it would work better for Enceladus.