As you know, I used vintage postcards for our wedding RSVPs. My plan was to then re-use them for thank you notes and send them back to the original invitee. Yay for recycling!
I used basic photo corners on craft paper cards and I think they turned out great:
I printed out a wrap-around address label I found on The Fussy Designer (she hasn't posted in awhile, but the labels are still available at that link.) Here's the back:
I also included a photo of me and Bill holding the Stanley Cup because, well, it's totally awesome!