Get your Winter Veil quests done despite the crowds
The first day -- or first few days -- of any in-game holiday is always busy. Sometimes it's so busy (as above), that the number of people crowded in on their mounts makes it impossible to see or interact with the questgivers. Complaints on the official forums have drawn out Bashiok, who offers a couple of solutions to the problem:
An easy workaround though is enabling nameplates for friendly characters (default Shift+V) and then right click on the nameplate of the NPC you're wanting to interact with.
Of course most people in these crowds are probably just trying to get their quests done like you are, so chances are you'll get more traction by bringing up nameplates with Shift+V -- or waiting for a few days until the excitement calms down.