We've been running a lot of shorter campaigns since we finished a 2 year long Strahd game (4-6 months, maybe 12-18 sessions each). We have a running list of 6-8 one paragraph pitch notes that people can choose, and we've been pretty much going with majority rules when one game ends and selecting what other game starts. We also run two games side by side (2 weeks on-2 weeks off) so people don't get burned out setting up or playing games. We also have a pool of 5 or so GMs in our 7 person group, so there's always people and always ideas. Some people live for 5E, so they always put up 5E, others like to run different systems and therefore we get to try new things. It works out pretty well for us.