Personally i wouldn't force it... i actually find it a bit ironic that mum's warn of "stranger danger" yet happily plop their child on an strange old man's lap who sometimes gives out lollies (again we teach not to take sweets from strangers) and expect them to smile!

We tried it the first year and my DS wasn't too happy, he's never been big on touching anyone but family, and i was fine with that, we did it more for the family than anything else, but now i just take a nice picture of the boys in christmas outfits in the backyard or similar and post it with handmade cards ("made" by my ds) to relatives.