Does anyone happen to know the encounter(s) that has (have) the largest map? That is, which of all official (i.e., non-user-created) encounters has (have) the most spaces, summed across all of the map tiles in the encounter(s)?

I think it's the Shadow Vault quest from The Shadow Rune Campaign. For that we had to figure out how it will fit on our largest table. But the other Interlude from the same campaign - The Overlord Revealed needs large space as well.

The first encounters of Armed to the Teeth and Profane Nexus are big as well, but not as big as The Shadow Vault.