We've done pictures while on vacation, pjs in front of the Christmas tree - did that when they were little and again last year at 16, 13, 11 and 8--cute!
Outside in front of a natural area? Beach, wooded area, park, fountain, in front of the fireplace, outdoor or indoor Christmas display? I always take a series of several 8 to 10 and then weed down to the best one.
Or if you can't get one good one of them together do individual pictures of the kids and put on same card.
Or maybe some cute caption with the least bad of the bad or ask the kids to pose pouting or something and say "Bah Humbug" or something like that.