I'm going to go out on a limb here... why not just take the bus directly to MK from OKW? The buses drop you off just a short walk from the main entrance, so you don't have to deal with driving yourself, parking, taking the tram to the TTC, and taking the monorail or ferry whenever one happens to arrive. After dinner at 'Ohana, take a nice monorail ride back to MK, enjoying the view around the lagoon, with lit up resorts at night... then hop on a bus back to OKW.
For the other parks, sometimes I think it's worth it to drive, but if I'm staying onsite, I tend to lean toward buses for MK...