I have been on several. The were each a day trip where we took a bus and went to 2 or 3 different shops. Once there we each just walk around and you can buy from the shop if you desire. Some people purchase a lot, others do not buy at all. Sometimes the shop will give a demo and offer special deals. On the bus, the guild or group that organized the trip will often provide snacks, drinks, and door prizes. We go to a restaurant for our lunch, which sometimes is included in the price of the trip, and other times each person pays their own.
Basically, it is just a fun way to go to a quilt shop with other quilters.