I have a feeling that you are going to have an awesome time whatever you choose to do. Since you aren't going until winter, I can run downtown in Omaha with my 8mm fisheye and 7D and snap a couple of shots just to kid of show you want it will do when it comes to distortion. It is a fun lens but takes a little bit to get use to and adjust to. The focusing is the hardest part. I'll keep you posted when I get a chance.

The suggestion of the canon 10-whatever you would like would be a great option if you were able to get there. I think it may provide you more of an experience. You have to stop down the fisheye quite a bit to get sharp results...i'm thinking f/8+ range.