I agree that planning is the way to go. My DH (and a few friends we've traveled with) used to think I was crazy, but now realize that we can get more accomplished this way. DH gets a kick out of it now, especially how excited I get

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In fact, last year we went to Vegas and I did research, but didn't plan a daily itinerary and when we met friends of ours there, they were disappointed/surprised because I hadn't come with my usual planner. I had read enough though that I knew what to do and where to go

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I especially think it's helpful for any theme park style vacation. If you research, you can really find the best ways to travel through the parks, so that you can get more done and not miss something that you want to see.
I love watching the travel channel specials and watch them whenever they are on, even though I've seen them before

. They were on earlier this week and I dvr'd them, so that I can watch them anytime up until our trip in...64 days
So I say...plan, plan, plan...just leave some flexibility in your plan for the unexpected. If possible, I allow one freebie day to do whatever, which sometimes is used for visiting all the parks and our favorites one last time

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ENJOY!