A couple of thoughts:

Perhaps we can choose one of the broader theme categories first? Then after the category has been decided vote on the various possibilities within that theme category? That'd be two polls. Unless it's possible to put all options in one poll, that is. In which case go with that because it would be one less poll.

As to the frequency can we vote on this just once and get it over with for each period of time? So not "when should the next one be" but "how often should these occur from this point on." That would save doing this every time. If we do it all, that is.