Last year we went to DL for vacation. We arrived in OC in the late afternoon (4PM) and were going to hold off going to the park the first day and just go to DTD to get into the Disney spirit.... well, that didnt happen. As soon as we walked under the archway and heard the soundtrack there was no way to hold back! We spent an extra $100 for 1 day passes and you know, it was well worth it! We still had 8 hours in the park. We rode everything in fantasyland, BTMRR, PotC, HM, Jungle Cruise, Indy (remember DL!) and IASW, (many rides more than once!) AND watched fantasmic. It was a great start to our trip. It was a good thing we had this fun filled afternoon/evening because it rained 16" the next 4 days!
My advice, MK first day, gotta go see Mickey! But hey, what do i know? I've only been to DL!