First of all, this is an item I still struggle with myself at times. The hardest part for me is often how to pace myself, which brings me to tip nr 1.
1. Pace yourself - The number of dance hours one can reasonably survive at an intensive event is directly related to the event type, the number of days/hours of actual dancing, the kind of dance classes booked and the intensity of the workshops you teach/take.
Often it is easier to do more hours per day if all classes are held in the same venue, and if they are combined with stretching/cool down at the end of the day. (even if this means hotel room stretching!)
Other things to consider are travel situation and timing, your personal fitness level (not always predictable!) and last but not least.. the amount of sleep you'll reasonably have had.. My general tip would be to not overbook if at all possible and prioritize instead, keep a max of about 2-3 workshops per day and give yourself permission to add more classes on the go if you can.
2. Prepare - A good preparation is worth half the battle.The more you are able to plan where you will be and what you will do, the more head space will be free to optimally enjoy the event experience. For me personally this means making lists. Many, many lists. A pre-packing list (to see if anything needs to be purchased before traveling), an actual packing list (extra practice tops/sports bras are always good to have!), a to-do list, a travel schedule, a list of locations, a list of classes and topics content/titles (to take and teach) and a list of snacks and such to bring (see nr 3). A notebook and/or camera can be helpful to retain the class material itself.
3. Eat wisely - Make sure you have a 'good' breakfast (for a long day of dancing you will need sufficient proteins) and that you stay hydrated well throughout the day. This goes double if the event is held during summer, if the classes you are teaching/taking are physically taxing and/or if the event is spanning several days. Good snacks to have on hand are nuts/nut-raisin mixes, bananas, water, sport drinks (there are tips online to make your own gatorade), tuna/chicken salads (protein! leafy greens!) And um.. if the going gets tough.. Caffeinated drinks ;) But be sure to hydrate extra in that case.
4. S.L.E.E.P - and stretch. Each and every day. Speaks for itself.. But really really.. DO IT! It helps reduce injury risk, keeps your brain capable of retaining/taking up information and your body will thank you by listening to you and staying more energized throughout.
5. And last but not least: Makeup and care. As a performer/teacher at events, grooming well goes without saying! But making a bit of extra time for cleanup and makeup at the start of each day (taking extra care of your skin in the evening and planning your dance wear saves time for this in the morning as well) really helps to get and stay(!) in 'dance mode' during the day. A bit of self-pampering helps to relax and feel your best, as events can get hectic, especially for closet introverts like me ;)