the DD disney buses no longer go to the parks - too many people did what you are suggesting - so you need to take a bus to a WDW hotel -
MK - that you pick a MK resort - Poly, COnt, Gf are all on the monrail
Epcot/Studios - BC/YC, D/S, BW - you get into Epcot by the International gateway - these are also the resorts for the Studios - you can walk or take the boat to the parks
AK - then AKL or the All stars resort
sorry but WDW transportation got tire of off-site buses dropping their guest off at DD and then telling them to take WDW transportation - so now you need to go to a WDW resort before you can go to a park... although this might be a quicker route than waiting for the DD bus-since all the DD resorts share a bus...
I think too - this is probably good marketing - off-site guests now have to see a WDW resort and I think they are hoping that next year these guest will stay on-site...