Chris, no doubt you will track down that elusive "Holiday Feeling" book! If you feel the collection is complete then that is all that matters. Who cares what someone else says it should be. There will always be something to add though imo.
Personally, I wouldn't consider a record, sticker, postcard, tattoo, matchbook, premium, pin, and others as a must for a "card" collection, but collectors should collect what they like. I just picked up a couple NYY fan club premiums of Mick that I had never seen before. I doubt they are on any Mick list, but I like them
Good Luck!