Hi,
I was just wandering through and saw your post. I do a bit of it myself.
I did a scrapbook for my parent's 40th anniversary last August. It was a whole retrospective of their lives though. I did come across a really cool idea for an event scrapbook while I was searching out format ideas. It was an album that was done like an alphabet book. The example I saw was of a wedding but it could sure be done for a birthday, too. They began by gathering all the possible words that began with each letter that had to do with the event, such as B: Bride, bouquet, bow tie, balloon sculpture, etc. then chose one to highlight on a page. Then they made the B page by putting a photo of the bride and "B is for Bride" on it but also had the other words just scattered around written on the same page of paper. What you ended up with was a book that had 26 pages in it as well as a title page and a final page. I would probably embellished the words on the page too by adding little pictures of some of the words. I would have put a little bow tie sticker or drawn a bow tie next to the word on the B page as an example or a little balloon sticker next to the word balloon sculpture. It was a great way to focus on a single event. I'm sure I'll do something like that in the future because I liked it so much.
Happy scrapping whatever you decide to do!