We drive from New Orleans, usually over 2 days, although we've also driven the whole way, though I doubt we'll do that again. Usually driven to Tallahassee, and then to WDW the next day. Did a better plan this time, spending the night in Lake City, FL. Result: Much earlier arrival at WDW, more bang for the buck.
As to why to drive? We had gotten our reservations prior to the institution of the new and discriminatory parking fees, so I'll have to run the numbers again, but driving with a hotel stay has always been cheaper than flying. Plus, family tradition: I first went with my parents and family back in the early 1970s, on a memorable trip that took in the Atlantic Coast on the way to WDW, and the Gulf Coast on the way home. Every time I went with my parents, we drove. And every time I went with my wife, and later our family, I drove.
On site, in the bubble. In our early marriage, we would go off property pretty regularly to eat, and other things. Not so much since arrival of kid, since we went all out on character dining.
We do go off property for Mass, and also to check out souvenirs. My wife loves the new Wal Mart off 192 at Westgate. So many souvenirs, and so many useful items to get, if needed. But that usually means off-property 3-4 times of late.
We drive all over the property when we go to WDW: Character meals for breakfast and dinner, but also the theme parks, Disney Springs, and the water parks (Park Hopper Plus). Free parking everywhere makes it very easy. It's a lot easier to jump in the car from where ever we are (except MK, where a boat ride will do) to get to Ft. Wilderness for the Hoop Dee Doo Revue, for example. No waiting for busses. We're walking up to Typhoon Lagoon in 10 minutes from leaving the hotel. I've found it is 99.99% of the time faster to drive to 3 of the parks: Animal Kingdom, Hollywood Studios and Epcot, than taking a bus. The exception is Magic Kingdom, heh, not because we're usually at a monorail resort. Here, the busses take you right to the door of the park, bypassing the need for the monorail or ferry. The result: I usually still drive, but it's usually a wash, with there being plenty of times the bus is faster, but also times that the car is faster as well.
We also used the buses more in the pre-kid era back when Pleasure Island was still a thing, as one could drink without worrying about driving. There's been plenty times when we're planning to only park hop between Epcot and MK, where we've parked at MK, and then used the monorail to shuttle between the parks. Makes me wonder about adding the new gondola onto that mix in the future.
But we're going to have to crunch numbers next time to see how it all plays out with the new fees, or any increases in the fees.