Just last Saturday night we did an Illuminations cruise (pontoon boat leaving from the Yacht and Beach club marina). We had taken the boat from the Epcot International Gateway to the marina. When we got on at the IG at Epcot, the captain said the boat would take 45 minutes to get to MGM. The Y&BC marina was the second stop from the IG, it was very quick. (I think the Boardwalk was first.) When we took our pontoon cruise, Captain Ron took us on a tour all the way from Y&BC to MGM and then back to Epcot to anchor under the bridge for Illuminations. He showed us the walking path and said it was 1 and a 1/2 miles walk from MGM to Epcot. How long would that take you? If it is less than 45 minutes, it is less than the boat--but it might be too tiring or take longer after a day of walking in the parks--your call. I know if it was me, with no kids--depending on how tired I was I would then decide which way to take. I think a combination of boat and walking as mentioned upthread would be nice. I will also mention that there was quite a crowd waiting to get on the Epcot/resort boat at MGM when we motored by on our private pontoon cruise. (We could still hear/see that Fantasmic was still going on as we went by too.)