I have mixed emotions about extended warranties. I never buy them on large appliances, but wouldn't buy a laptop without one. I bought one on a brand new 1995 Honda Del Sol for 4 years and never collected a dollar, but that was a Honda. I just bought a 2006 PC 2551 with 3,500 miles and just bought a minimum coverage ($500 deductible) policy from Good Sam for $300 just to cover any catastrophic failure, since my unit is clearly out of warranty. As has been referenced in your other response, they obviously make money for the insurance company. I would say buy one only if you would be VERY unhappy if something failed that wasn't covered and you had to lay out the bucks on it.
On your comment about visiting the national parks out west, I have a couple of comments. First, I hope you're planning to tow a car, as you are severely limited on how large a vehicle you can drive on Going to the Sun Road in Glacier. Also, I would not go to Glacier without visiting Waterton Park, the partner park to Glacier in Canada. You will, of course, now need passports to enter Canada and vaccination papers for any pets on board. There is a very nice campground in the middle of Waterton Township and you can visit the Prince of Wales for a nice meal if you want. Also, not too far north of Waterton is "Head smashed in buffalo jump", a world heritage landmark, and the restored Mountie fort at Fort McLeod. A three hour drive north of Waterton takes you to Mt. Kidd RV Park on the Kananaskis Parkway, my vote for the best campground I've ever visited. Check their website for reservations, as they are VERY popular. The Kananaskis Country is as beautiful as Banff and Lake Louise, but without the tourists. Enjoy your trip.