The Disney bus system is clearly not up to the task of moving people when it's busy (greater then 6 out of 10). The bus arrival times are inconsistent and the wait can be longer than 20 minutes. We used a taxi (that was sitting right at the Port Orleans main building) to get to the Contemporary for a Chef Mickey dinner reservation at 6:10pm. It was great. Very quick and door to door. It was $13.60 and I gave him a $20. Best $20 I spent all week.
Taking a taxi to MK is not feasible as you have to go the Contemporary and then walk over. Might as well wait for the bus. But I'm thinking that next time we'll use the taxis to get to AK, HS and Epcot. Depends how much time you can waste waiting for the busses.
The other annoying thing with Riverside busses is that they go in the wrong direction when returning from the parks. They drive right by the South (main) depot, go around riverside to pick up more people in an already packed bus, and then stop at the South depot last. EVERY bus we rode had at least 80% of the people get off at the South depot. Their path is neither logical or economical. All they would need to do is to have the riders tell the driver which stop they want and then he or she can adjust the route. It would be better for everyone.