You should definately get a waterproof P&S and bring it along! I did, and gave it to my wife or my son depending on the attraction. They got some shots I never did, and I had a backup camera if mine would fail (30D with 17-50 lens). Also, they take almost no space in your bag.
That way, your spouse can take pics of you from the side, and you can take pics while in the ride, and not worry about your DSLR.
I have had good experiences with Olympus offerings in Waterproof P&S.
All in all, it was a great day, and to be able to choose from two cameras pics was luxury when I came home.