If your from Canada the "cold" of the Bay Area won't be as much a factor as it would be for others. The Bay has some big winds which could make for some fun sailing. I'd say go for the J-world. If you want some warmth San Diego is an option also.
One difference though is the bay will be home to strong consistent winds very different from Mountain Sailing, which carries a unique set of skills probably not repeated at many schools. After all who would want to pay for a week long seminar in fluky shifty winds.
J-school teaches on the J-80 which is a blast. However it is a more modern design than you will see on most inland sailing venues. They are easier to sail especially under-crewed and easier to sail up to their rating than some older styles. One thing to consider though is some of the tactics and angles (the boat sails) are different in these type of boats so check with the school to make sure they will help explain the differences between what you are learning and how it applies to a SJ24.
I am not sure of what I am more jealous of, a week of cruising out of Vancouver or a week of racing in the Bay?