A big thanks to everyone who posted pictures or advice on passport STDs. Mine are complete and went in the post yesterday.
Here is a photo: (I hope!)
I did the cover using yellow cardstock for the cover and used plain paper for the insides but the "dotty" pattern made it look yellow. The lovely ladies in the printroom at work offered to do all the printing for me so that has only set me back a box of chocs.
Instead of envelopes I used small polythene bags and created address labels to go inside them, then stuck them down. This was much cheaper than using envelopes and I thought it was nice that you could see the design as soon as it drops through the door.
Finally, I had a problem with "personalising" each passport with the names of the invited whilst keeping with the passport theme. So I came up with the idea of having a "baggage label" like the ones which they stick to the back of your passport for baggage reclaim. It wa a bit different and I think it works.
I have attached both templates for your use, they are in publisher format and I have downloaded some fonts so it might not look exactly as it does in the photos if you don't have those fonts. Also the design is a hybrid between a French and UK passport so some of the details are a bit different from your US ones.
I hope this is of use to someone,