Basically the topic. For me it would be Quantum Leap. There are a ton of shows on TV now that are all about the season long story arcs and I like that but sometimes it's nice to have a show where if you missed an episode it really doesn't matter. Or maybe I'm watching all the wrong shows. Still throw that together with the idea of time travelling do gooders, a bit of social or political commentary and just general highjinks and you get well fun. Doesn't necessarily need the old cast back either.