Karen I think you should do whatever makes YOU (and your bf) feel most comfortable and secure. If that means a "plan B" pill (which I assume is like the morning after pill?) then sure... go ahead as I live by the mantra that it's always better to be safe than sorry I reckon.
Have you considered getting a rod inserted? I was listening to a health program the other week and they were talking about how doctors really are moving away from DP shots in favour of rod insertion - since they last for 3 years and deliver a measured dose, and you don't have to worry about going back every 3 months for a shot. Just a thought
I hope the hotel is awesome and you both celebrate new year's in style!!!