Well, the locations are always nice and a little two day vacation is good for everyone but sometimes the event is held on a weekend. Getting out of it is a little complicated and so sometimes you are spending shabbat in a hotel far from family. The first hurdle is making sure you can get a room with a manual key. Mention this as early as possible to your retreat organizer. Otherwise you may end up locked in your room, with a roommate who is entirely confused about the situation. Sometimes the retreat is held on friday and you need to duck out early to get home in time. Faculty members who often drive t the retreat are good people to hit up for rides. Sometimes it's a monday/tuesday etc. and you are sitting pretty.
Food is your next big issue. Most of these places have some sort of kosher option that you should mention to your retreat organizer they should order for you. I would reccomend dbringing some food anyway until you have been to the location at least once and know the food. Often you must hunt down a waiter and ask him to find your food. Everyone else is eating a giant meal and you are waiting 30 minutes for yours to heat up. You don't really mind but everyone else at the table is concerned for you. Reassure them at the first meal, make light of it and then hopefully they will forget it for the rest of the meals and the waiters will know to look out for you. You can even ask them to start the heating ten minutes before you are supposed to arrive.
Portion sizes vary widely. You may still be hungry at some places - seek out the fruit. There is usually a giant bowl of apples, oranges and bananas that will become your best friend. At other places there may be too much food. Place after saran wrapped arrive at your table and you grow embarrassed at your bounty. Share. For some reason everyone at the table wants to try the kosher food. Let them. Sometimes they heat the food incorrectly - removing it from the packaging or placing it after heating onto a china plate. This is usually some well meaning, but newly hired waiter who wanted things to look nicer. Tell him what the problem is so that you don't have to deal with it again at the next meal. Sometimes there is a cold part of the meal that is still OK. Other times you have just lost your meal. That's why I usually bring a little food with and horde snacks like granola bars and oreos when they are offered.
Other than these issues you tend to have a nice time. Meet some new people, hear some interesting work, see a beautiful hotel. In fact I am currently from just such a retreat, and this time of year rooms here go for 500-600 dollars a night. There are some social hours but you will not be the only person not drinking. There's usually one mormon or teetotaler besides for you. People get over that pretty quickly.
Have a retreat in NY coming up? Chances are I may have been to your location. If your curious, shoot me an e-mail an I'll let you know.