I would also look to see how much a rental car would be. You may be shocked at how much just a few cab rides may cost you! From the airport to a Disney resort is roughly $50, from Disney to Marriott's Grande Vista for me one night was $50 also! And yes, I know my way around so he wasn't taking some long route, it's just that night my DH dropped me and the kids off at the MK to meet up with my friend and her kids (husbands did other things that night).
You can frequently find good deals on cars in Orlando - and unless I'm staying AT a Disney resort I would definitely have a car.
Plus, if you do decide to do shopping, and you end up with a couple bags, you can store them in the trunk and drive somewhere for dinner. You won't be stuck taking the trolly carrying bags with you. I think you'd have more freedom with a car.