The absolute highest fare you could ever get on property for a taxi ride is about $30 (for Animal Kingdom Lodge to the Grand Floridian). Most trips are under $20. Most of the hotels are just not that far from the rest of the park. Boardwalk to Contemporary, for example, is $20.
And, of course, renting a car is an option. Even for one meal you can often find deals for a one-day rental that actually net out cheaper than taking a taxi. This only is really convenient, though, if you're staying in the Epcot resort area and can walk over to the Dolphin to pick up the car, or are staying at a Downtown Disney area hotel and use one of their rental desks.
For me, taking Disney transportation from resort to resort is maddening. Waiting for one bus is annoying enough; two busses (or one bus and one monorail/boat) is just too much. The only time I'll do it is from one monorail resort to another, or the Contemporary to WL by boat. From Grand Floridian to WL, I take a cab. It's like $6.
The idea of going to the nearest park and walking is great for the Contemporary, but not much else. The walk from the DHS bus stop to the Boardwalk is probably the next best walk, and that's a good 15-20 minutes. Add another 5 minutes to get to the Beach Club. It's probably even further from the Epcot bus stops (plus you have to enter and exit the park).
When you're spending thousands of dollars to come to WDW, I can't understand spending an hour using Disney transport when a taxi or rental car is soooooooo much faster. But everyone is different. It just comes down to time vs. money.
