Wow...what a question.
Mike Sweeney is correct that Bedford Springs is a Doak Scale 6.5 or so in my opinion...it's an architectural history afficianado's wet dream and lots of fun, only held back by too many forced carries over wetlands. It also has 5 of the best par threes you'll ever see, as well as possibly the worst opening hole on the planet.
Nemacolin, on the other hand, is NOT Pete Dye at his best, on a tough, rocky property.
On the other hand, Nemacolin offers mucho amenities for your fiance and if the trip is about as much romance as golf I'd have to side with that one.