This is a great promotion by the Google Apps product marketing manager. I took a look at the templates and don't really need any of them right now, I'm comfortable enough creating my own as I need them for now, but just wanted to put it here for revisiting at a later point.
The rough guest list and budget are being held at My Wedding Workbook (from A Practical Wedding's endorsement). It's good enough, though I wish it were more customizable to remove all the line items we feel are unnecessary. For example, the budgets section is broken down not only to ceremony and reception, but bridesmaids' luncheon, post-wedding brunch, bridal shower, etc. No need for all those, and yet reception food is just one line item, without alcohol being broken out separately?