Good morning, It might be difficult to get reservations in Sisters, but you might try some of the outlying towns - I usually stay with a friend or make it a day trip from Beaverton so lodging has never been an issue. As far as transportation to the show, you might try checking some of the local quilt shops because some of them run busses over there for a day trip. I know that Fabric Depot in Portland usually takes a bus over. I think the cost for the trip is usually about $75 (more or less).
My must haves for the trip are - comfortable clothing (it gets warm), good walking shoes, my camera and I usually pack a lunch. Getting there early and walking as much as you can in the morning while it is still cool is the best. They usually have water stations and plenty of areas that you can sit and relax. I like using my neck cooler when it gets warmer in the afternoon.
I have to admit that it is much easier with your own car - I keep a cooler full of water bottles and ice (and our lunches) and we have been known to go back just to sit in the air conditioning - lol. Last year, we moved the car from the coveted parking spot over to the city park and spread out a quilt on the lawn for our lunch. My daughter treated my girlfriend and I by making our sandwiches and serving us while we sat and relaxed. It was almost like being in a restaurant, only better.