I am quite certain Green Gables is the only Thompson on PEI as well. In fact I believe it was Cooke that redid some holes a few years ago so I am not sure how much of Thompson's design is still there. Robert T, Jeff or Ian may know better.
Bill, the best thing about PEI in my opinion is that you can access about 2 dozen course from within an hour of Charlottetown. Granted not all are top notch courses but there is enough there to keep you interested. McBroom, Furber, Cooke, Hurdzan have all done work there. There is a pretty good web site that they have put together for reference. www. golfpei.ca
Dave