This may sound counter-intuitive to what I'm trying to communicate, but the best way to let loose on the day/days you will be visiting a Disney park is to plan ahead. Know your travel plans well, work out a trip budget, and think ahead as to what your plans are for meals. By the time you get to the park, you shouldn't be thinking about how to get back to your hotel or whether you will leave the park for lunch. You don't have to plan precisely, but do sketch out a rough plan.
Know that you can go to a Disney theme park on a small budget. If you drive to Disney, bring picnic food and stow it in your car or hotel room. Or, bring granola bars, sandwiches, and your own bottled water (which is allowed into the park) and stow it in a locker until lunch time! There are ways to avoid the high food prices. Also, there are places to eat fairly cheap. For example, at Disneyland and Disney World, there are fruit and snack stands in the Adventureland areas. These offer cheaper food, such as vegetables, apples, pineapple cores, and trail mix. The food is much more refreshing on a hot day than a burger and fries, healthier, and always cheaper! So consider re-fueling with healthy snacks several times throughout the day instead of eating three big meals.
USE THE FASTPASS SYSTEM! So many people don't that it shocks me. Disney has invented a system called "Fastpass" that allows you to insert your park ticket (so hold onto it!) and recieve a "fastpass" for a ride sometime within the next hour. In other words, you get a pass to get out of waiting in line. There is still some waiting involved, but it's usually at least one fourth of the time, and you don't have to swelter in the heat or get claustrophobic. You can only get one fastpass at a time, but you can get them for each hour chunk of the day. So many people pass this up because it intimidates them for some reason. Try it, you will have a much more pleasant day!
Know which rides you want to ride. This sounds silly, but make a list before you even go on your trip of what rides you really want to ride, then hit those first. Line length can differ drastically at Disney from day to day, so make sure to get your favorites in first, just in case.
As Andy Richter would say, "Check your eggo at the door". Meaning, of course, lose some of your grown up inhibitions. Not all of them, no nudity permitted. But do be willing to laugh and play and enjoy yourself. Know that nobody at Disneyland or Disney World is going to make fun of you. Honestly, if you make a silly face, or tear up out of sentimentality, or sing along to a song, everyone else is distracted by their own good time. Make an effort to get out of grown-up mode! Forget work and bills and problems, just for a day!
Take pictures! These are the best souvenirs and they are free! Take advantage of the photo ops provided by Disney, such as King Arthur's sword, or character moments, or statues. These are not just for the kiddos!
If you can swing it, stay at a Disney hotel. They provide excellent transportation to and from the parks, and it's part of the hotel fees, so you don't have to pay out of pocket. It takes worrying about parking and trams and shuttles to and from outside hotels totally off of your mind. This will help you de-stress and enjoy.
Ride during the lunch hour. Everyone else is eating, lines are much shorter. If you are going as an adult without kids, you can eat on your own schedule!
If you are there in the summer and need a break during the day, take it when it's hot. Around 2:00 - 5:00 or 6:00. Go home, take a dip, come back refreshed and ready to stay till closing time. Most families with kids have to leave early so the little ones can catch some shut eye. But if you are there on a honeymoon or birthday trip without the little ones, arrange to stay up late. Disney parks are breathtakingly beautiful at night.
Get there EARLY! Be one of those dorks who arrives at the park a few minutes befoe it opens, you will be able to run right in and get on one or two rides with no lines at all. If you are staying at a Disney hotel, take advantage of extra magic hours, where they open the park early or keep it open late especially for hotel guests. Again, staying at a Disney hotel may look more expensive than local franschise hotels, but it offers the best deals and sweetest perks. It's cheaper in the long run.
Save the sleeping for a trip to the beach. Go to Disney and be ready to go out there and have fun. If what you need is rest and relaxation, consider a different vacation. Not that it isn't extremely resting to reconnect with your childhood...you will coming home feeling tired but invigorated.
Try to catch at least one fine dining experience at Disney. Their restaurants are wonderful, this is something that you wouldn't have appreciated as a kid. But you will feel lavished upon as an adult between the cuisine, environment, and service. Trust me, Disney knows how to treat us crazy grown-ups!
