How about the original idea, "Wagon Train to the Stars"?
Lets take "Little House on the Prairie" and find a way to convert it to Star Trek. A family of pioneers settles on a planet, and while they try to build their home they encounter a bunch of science fiction horrors that they need to deal with.
I would not buy that. If you really want to set it on a planet, give us some outpost on another galaxy, like maybe they found a wormhole to the Large or Small Magellanic Clouds, or maybe the Andromeda Galaxy, and they make a permanent outpost(city) on a planet there. Give the outpost two-three star ships that they can use to explore the new territories. What would give us this situation: first of all this shouldn't be a BIG departure from the Milky Way because they could anytime come back and have adventures/missions on familiar territories, but also they could have a strange new world to explore, and some different settings relatively to the other series. It is a mixed concept of DS9 and Voyager, as they would have permanent settlement to go to, but also star ships for exploration. The sets should be constructed in a way so that with a little change they could look like the bridge for two different ships or observatory for two different ship. I hope you get the idea. The settings might seam similar to SG:A but that would be far fetched as saying Firefly is like Star Trek because it is set on a star ship, so I think the idea would work ...