You're right that the hymns and service at Christmas provide a continuity that overrides unfamiliar or uncomfortable churches, and helps mitigate the stress of preparation and travelling. However, my son and I would take issue with the notion that this is accomplished by means of familiar lyrics to carols and hymns. Many of the most familiar have been tweaked (with the best of intentions) to suit modern sensibilities regarding inclusion of all of God's people.
Unfortunately, they've been tweaked differently in different publications. Thus, by the time one sings a carol for the 4th or 5th time (at 3 different venues), one ends up either singing the oldest, most familiar words, or in the case of a carol known in both English and its own native language, being seriously tempted to revert to the original French or German and avoid all the problems!
St Anne's Episcopal (Reston, Virginia)
Herndon, Virginia, USA
31 December 2012