I just typed in Windsor Hills to Disney Springs in the Uber app and its estimating a fare of roughly $22 for an UberXL. Obviously, this cost will vary depending on exactly where in Windsor Hills your pick-up is, which park you're going to, if surge pricing is in effect. etc. But for the sake of estimation, lets round to $25 per UberXL per trip for round numbers. By the time you go to each of the 4 parks and Disney Springs twice, you'd be roughly at $600 in Uber fares. Add another $200 for roundtrip airport transportation in two UberXLs. Add another $200 to estimate for variables like
Walmart, outlets, restaurants, etc. That would put you at roughly $1000 in Uber fares, estimating high and understanding there's many variables but you can narrow it down by using your exact address of where you're staying. Using Uber would still be roughly $700 cheaper than renting a car and paying for parking. You lose some flexibility by not having your own car, but Uber is almost always readily available and you still have flexibility within that
budget to use Uber more if needed.
Is there 8 of you total? You could also likely squeeze into UberX's - 3 in the back, 1 in the front. Wouldn't work to and from the airport with luggage, but I have frequently squeezed in UberX's with my husband and parents and its been fine. Never had to turn one away. UberX would be even cheaper than XL.
As an alternative option, at least for the airport transfers, is hiring Tony Hinds. Him and his drivers drive 12 passenger vans. He charges one flat rate so it doesn't matter how many people you have, and he includes a complimentary 30 minute grocery stop which would eliminate the need for a Walmart run. His pricing is on par with other private car services, but since you can all fit in the same van, it would probably cheaper than relying on UberXL to and from the airport. He also will assist with luggage inside the airport.