Sir Brennen
Legend
Since all we have here are stat blocks, I'm guessing the lair features will be included in the additional fluff text for the creatures, or perhaps in a more general "dragon" section before the individual entries in the Basic PDF and/or Monster Manual.That said, in the original design, they were talking about making them more... interesting and tied to their lairs, which doesn't really shine through here. The dragons in particular are way more similar to each other than, say, the Monster Vault dragons.
The HotDQ (which I keep thinking is a weird internet abbreviation for Dairy Queen hot dogs) might have lair setups as part of the adventure text itself.