Depending on how late you get in the first night, I might go to Downtown Disney and get a flavor of Disney there. The first day in the parks is always MK. When you look down Main Street and see the castle at the end, you know you're there. Be there at rope drop for the ceremony, it's pretty cool. Your first time, you want to be immersed in everything Disney, but don't forget to see all the little things, like hidden Mickey's and so much more in the details. To me, that's what Disney is all about, the details. After hitting a few rides in MK, skedaddle out of there because weekends are the busiest days at the MK. Park hop over to another you may have an interest in. Use Touringplans or another place on the internet,just do a search "best days to visit park Walt Disney World" and it will guide you into a site to let you know which park historically is best on which day. We have used this method and NEVER waited more than 20 minutes for anything, even in summer months. Take your time and enjoy it all. DO NOT do COMMANDO. It will wear you out and you'll lose some of the enjoyment. Besides, once you've been there once, you'll be back. Heck, we decided to move here! Have fun!