My holiday cards have been for many years photo cards of me and my wife in places we've been during the year, whereas the calligraphy is usually on the envelope. This is this year's design, to which I added some details on some of them.
In general, I try to allow room for the stamp to be cancelled such that it does not interfere with the design (worked well this year) and allow some room at the bottom for the inevitable bar code the USPO puts on everything that goes through the machine sorter. That didn't work so well this year. Perhaps the machine misread the zip code, as a double second code was plastered over the original one (and part of the design). It did take two weeks to be delivered. Oh, well.