Congrats on your nephew! I got married over the summer and compiled some of my thoughts on wedding signature quilts on my blog - maybe it will be a little helpful. My one big take away is to recommend having people sign blocks that are trimmed with masking tape/artists tape and backed in freezer paper vs. having them sign a finished quilt. I was able to square up the blocks and make them look a lot neater I think especially since some of the signatures were a bit party-influenced....
Another thing is I thought I would need a block for every guest, but I really only needed a block for every family, since most people signed in groups - so I had extra blocks.
http://waterpenny.net/how-to-make-a-...gnature-quilt/