What published books have a decent collection of fun lairs?
There isn’t one yet, but I have slowly been making lairs (some with maps) on my web-site/blog:
Wow Thanks this will be my go to location for dynamic lairs from A to D from now on. 
Thanks for sharing.
If you can lay your hands on it, there is TSR9177 - REF3 Book of Lairs and TSR9198 - REF4 Book of Lairs II. Although these are for AD&D 1st Edition, I think you can use most of it without much fuss. I haven’t read them in a while, but as far as i can remember there are some good lairs/ideas in them; others are solala…