Here's another plan:
Tell her you really appreciate that she is willing to do this for you. And to show your appreciation, you are going to take her on a weekend that SHE would like to do. Then for your B'day, you are gonna gather up some of your buds and ride to see the Museum because you know she would not really enjoy that, but that is what you have your heart set on. This should be win-win.
TQ