you should get like an engraved electronics cover or something to commemorate the occasion, instead of it being an otherwise stock guitar. If you go the custom route, I say have something cool done to it while it's being made. I Don't want to assume you and you fiance are as odd as Angelina Jolie and Billie Bob Thorton but, you could have blood drawn and mixed into the paint like a DNA. THis is a little extreme but think how you'll always be connected to your future wife through this guitar.