I've been spending my vacations building mostly things from George RR Martin' fantasy series, A Song of Ice and Fire. The first project, Winterfell, took years of spring breaks and summer vacations to put together. It was ravaged to build other, smaller, sets also from Martin's world of Westeros. The Riverside Inn was the next large-ish project inspired by Martin's books.
Dragon's Lair is not from Westeros but I just had dragon that needed a home...
I design all my large-scale pieces as play sets, not models. That is, you are meant to have access to all parts of the creation. I like to see inner-workings of the places I design.
The Falcon Depot series was my first large-scale opus NOT inspired by Westeros. It has a working drawbridge and portcullis - listed as a separate MOC if you're interested in how it works - as well as a working winch system for loading supplies into the depot's postern gate (also with a working portcullis). The Depot was the main project and the Dragon Attack was a last minute idea, but it needed some excitement. The Green Dragon and the Green Serpent are straight from the Viking Lego sets. But the red, three-headed dragon was my own design (and he's hungry).
I've been starting a series of Westeros-inspired minifigures. I've got the Night's Watch, Robert vs. Rhaegar, and now Eddard and Tywin. If you are a fan of George RR Martin's books, I'm glad to take suggestions of other characters you'd like to see in lego form.
The idea for the Sea Cliff Hideout, another large opus not inspired by George RR Martin's works, came to me in a dream. I had been wanting to do a topographic project but couldn't think of an appropriate geological formation. One morning I woke with a profile view of a sea cliff with three tall, narrow islands spitting distance from the cliff. As I started the main design, I realized there was going to be a lot of wasted space if I just wanted to make it a topographic project. So I came up with the idea that it was a secret hideout. Then I had to invent a way that the hideout's occupants would enter. The last thing I wanted was a trap door on the surface; it's too easy to infiltrate. So I worked out the plans for the barbican tower and double drawbridge design.