Lots of places! I tend to find if you smile, they respond in kind in most places....
...but I especially recall last year, when camping around lake Khovsgol in Mongolia, several of us were quite desperate to watch one of the games during the World Cup, and came across this old man's home, which happened to have a TV...
It was late, he'd never met us before, but he ushered us into his one roomed house, invited us to sit on his only bed, share his vodka and unpasturised curdled milk chunks out of a hessian sack (not for the faint hearted), and grinned his way through the whole match. Amazing chap.
Friendliest welcome at immigration would have to be at Puerto Rico. Only, the chat each person in the queue had with the officer meant that it took a little while to get through... but you did get through smiling!