beagley,
I grew up within an hours drive of the Rocky Mountains, here in Canada, and as you can expect have been riding in, around, and through them for quite some time. Having been down into Montana and Washington
mountain ranges too which are similarly sceneric. Utah (Moab) is something else altogether.
As for maps, most local maps of the provinces should suffice, but specialty maps are always good. Likely googling will dig up lots of references online. A book of riding roads called Destination Highways is also a good bet. Google Maps will show you some topography. There is even a specialty store in our city that has every type of map you could want. If you're into techie stuff check out some of the latest GPS recievers -- some with full color maps!
Mountains being what they are (big and hard), road options can be limited to a few passes at times, and it can often be important to choose some roads far in advance or end up "stuck" on one side of a mountain range for hundreds of miles, whereas an earlier route through may allow you more options. Check this out in advance if it concerns you, otherwise just go with the flow. Talking with locals as you ride around often provides you the best info regarding fun roads or scenic places that are just a bit off the beaten path, as well as info on construction which can bog you down.
You shouldn't have a problem with fuel stops at all. It would take a concerted effort to not find fuel. The only caveat being some rare specific motorcycles with very short fuel range, which the bike you're choosing or similar models are designed for going long distance.
As for weather. September is inviting cooler weather, even August can be cold at times, and if you get soaked in the rain, well 50F is still cool at speed. It is much cooler at the higher altitudes, maybe 15-30F cooler at times, and the farther north you go the more likely you will run into inclement weather conditions.
The trick for comfort is to dress appropriately then you can ride in anything the bike can be ridden in. Full leathers and a rain-suit work very well for warmer stuff, but a syntethic suit or jacket/pants combo you can layer under, like an Aerostich are purpose built for all-weather touring. The layers cababilities make the difference. A couple pairs of gloves are good too. for changing conditions, and if one pair is soaked, yhou can change mid-day and dry then in the hotel. There are rain covers for boots and gloves (really the best ones I have are just like oversized dishwahing gloves, but black, and the boots are similar rubber things). If you wear leathers, some long johns (polypropylene, wool/poly blends are thin and toasty: like Thermax, Patagonia) can help alot. If you are wearing a synthethic cordura nylon blend of gear, than you should have more room for a layer of fleece if it's cold. Of course there's always electric vests and grips. I've only used the electric grips myself once, for a 24-hour ice race (very awesome!). One very important thing to remember is keeping drafts out of your clothes. On nice tidbit I wear is a fleece skiing/snowmobiling fleece "neck-tube" (dickie) in the cold months (they make ones that are nylon backed as well for more wind resistance). Often just a bandana wrapped around my neck in warmer fall or winter months is perfect. This makes tremendous difference in body temperature.
Hoteling is a safe bet to make your initial ride simpler, easier and thus more fun, although luggage space shouldn't be a concern if you want to go two-up camping, depending upon your sense of what is comfort and what is hardship. Anyway, late in the season is always easier to find places to drop for the night. In the areas I've been through there are always a myriad of small towns with everything from small bed-n-breakfasts and always larger motel/hotel chains... whatever suits your need. for reference, I've never booked hotels in advance no matter what time the year, but that's just me... likely I've forgotten times I had to dog around looking for a place for the nice after a rainy 500-mile day...
As for security, I've generally used a disc-lock except with my most difficult to start bikes (hee hee) even in the boonies, because although the risk of your bike being stolen is greatly reduced over the cities, if it does go missing the situation would be a lot worse.
If I remeber I'll dig up some photos from over the last few years to whet your appetite a little more
//monkey
