Welcome to the board, and you've sure picked a great destination for your trip. You've gotten some good advice-- no need to break the bank witha 700 dollar rod, but biting the bullet a bit now and going for a better rod seems like a good idea.
Just a word of caution, the Sage Fli has been discontinued and replaced by the Flight. You can find discounted Fli's for around 220 (2 piece) or 250ish (4 piece) as opposed to the Flights which are in the 300's.
As others have said, as a beginner you're not likely to notice much difference, but it would be good to get a rod that you can grow into as your casting improves.
I'm thinking the Reddington RS4 (around 170 for a 2 piece, 200 for a 4 piece) or the Fli for just a bit more if you could find a deal might be a good way to go. I would get a 4 piece for air travel if there's a chance you might be flying with it. The extra bucks for a better rod, in terms of your trip to Montana, will probably be a rounding error, but these are both good rods. Some of the less expensive beginning rods might be a bit easier and more forgiving to learn on, but as you get better and can aerialize (it that's a word) more line, they begin to feel pretty wimpy.
Where are you? Chances are you'll have a lot of fish to chase and time to practice before your trip.
I also highly recommend you checkout a local chapter of TU or FFF club in your area. They'll help take years off your learning curve casting clinics, gear, tackle, where/how to, and you'll meet folks that are into the sport and up on the fishing in your area
To look for a Trout Unlimited chapter: Council/Chapter Search | Trout Unlimited - Conserving coldwater fisheries
or club affiliated with the Federation of Fly Fishers: Locate a Club
Keep asking questions as they come up, lots of helpful folks here. And browse some of the FAQs and recent threads. There maybe some answers to questions you haven't even thought of yet.