Ahhh, vacation time.... Just wanted to share some friendly, unofficial, personal suggestions.
It probably the touchiest subject of our contracts, and is sometimes open to interpretation. I can't think of any two people in JLP (or JCP or Regional or whatever) who seem to have the same situation. A lot depends on the relationship that you have with your school, other contract obligations (like supplementary classes and camps), precedents set by the native language teachers who came before you (and if they abused the system), and how open you are about where/when you are going (the least said, the better).
Remember, your vacation days do not include weekends and are meant to be taken consecutively (my school tried - and failed - to make my vacation days be 3 days here, 2 days here, 3 days here etc, throughout the summer so that they could get me to do extra things).
Do not book a vacation until you have sat with your co-teacher (and a calendar) and verified when the exact vacation dates are and that you do not have extra classes or camps. Do not accept maybe for an answer when it comes to dates, act the "stupid foreigner" (Hmmm, I do not understand. I must be back on this date? etc) and be sure that everything is crystal clear before you begin booking trips.
Another thing to consider is that we do have a really sweet deal. If our schools really followed the contracts to the letter about vacations etc, we would end up with a lot less vacation days than we actually have.
Tips for negotiating in Korea:
1. Smile
2. Ask them to tell you when the best vacation dates are
3. Stand your ground, but don't be belligerant
4. Remember that "I do not understand" is your best friend
5. Cool it if things get too heated: It may take more than one meeting to sort it out
6. Keep it friendly
7. Don't tell them that you plan to leave for a month if you are only entitled to 2 weeks
Remember, yes, we are here to travel, but it's our jobs that pay the rent!