You can...you pay for the dining plan at hotel check in so all you have to do is give your rewards card to the CM and tell them what you want taken off your rewards card and what you want to put on a credit card. I had enough last summer to pay for the dining plan and then a few other things as well. The only place you might not be able to use your rewards card for a tip (I am not sure if you could or couldn't to be honest) would be if you were dining at some of the non-disney owned restaurants (like Raglan Road, Wolfgang Puck's etc, that accept the dining plan but are not disney owned)...you can definately use the rewards card for tips at Disney owned establishments.