I bought a traditional guest book, but am now deciding between 2 other options: either an autograph palm tree that I got from Oriental Trading Company or an autograph plate that has palm trees on it from Target. Not sure yet!
I have 4 friends in the wedding and 4 sisters in it, so I alternated friend-sister-friend-sister-etc. I matched up the guys with the girls according to height and also thought about if they knew each other at all.