I hardly ever get TLN,so a week is way to much for me. But I understand that some guys might like that. Just remember 4 things:
1) Try before you buy. Have a session with the girl first, then maybe TLN. Then, if you still like her, offer the week package. This is good for you and her. You determine if you are compatible and she determines if she can trust you to keep your word.
2)Don't be surprised if they flake on you. Inevitably some emergency with their mother, grandmother, son, daughter, brother, sister, etc, is going to come up and they will want to ditch you for a day or so. Of course they will expect to be paid the full amount even though they were only there 4 out of 7 days

. This leads to the next point.
3) DONT PAY UP FRONT: This is a sure fire way for her to ditch you as soon as possible. I personally think that paying by the day at the end of each day will work well. Depending on your relationship with her and her financial status, she may not want to wait until the very end of your trip to be paid.
4) Don't be surprised when YOU get bored. What seemed like a good idea at the time will change rapidly, once you find yourself surrounded by tons of availible women that will Phuck you senseless at the drop of a hat (and a few thousand colones). Eventually, you'll be trying to figure out ways to sneak away for a few hours to get some on the side.