Sounds like you have your info pretty dialed in. Two small changes, out of personal opinion, is that Big Sky does not have a good
park, they have an ok
park. It is fun sometimes, but don't have a picture in your mind of a super sick park or anything. (Bridger technically does have a park, but that is not really worth mentioning. It is essentially a couple boxes and rails, but they can be fun on down days i suppose) As far as terrain goes, I would prefer Bridger's terrain on a pow day and Big Sky's terrain on a groomer day.
Great Divide is a short ways north of Helena. I think it's roughly a two hour drive, but they have a fun park.
If I were to choose a pass between big sky and moonlight, I would go big sky for sure. Moonlight got a little stale after several days riding there last year. However, they do have sick rails, if that is what you are in to.
Riding one day at big sky and one day at bridger could be hit or miss. I've heard some people say that bridger sucks, but that is because they just hit on a down day, so don't judge your one day too critically.
Either way you go, I'm sure you'll have a good season. I had a pass to Bridger last year and was very happy. This year I have a pass to Big Sky due to the fact that a lot of my friends are going there and, I feel, it is more complete; I know a lot of die hard bridger fans will disagree. Big sky is sick on pow days, groomer days, and the park can be pretty fun. Don't get me wrong about bridger though, that place is way sick. I might end up with another pass there in the future. Ok, I feel like I am starting to ramble, so I'm gonna stop this post. Hopefully this info helps....