Thats a good question haha. Kinda tough to pinpoint but 1) Really liked the NON-instanced housing. That house, no one else in the game could own it, it was mine. 2) Wife and I really got into VG. It was our separate world, universe. We had as much stuff as we could afford to make it actually look like a house. Table, chairs, lighting, EVERYTHING. Wife would even decorate our houses for each holiday. We had Christmas trees during Christmas etc... 3) But I think why I really liked the housing was the stuff in the house, everything told a story of how it got there. We would look at items and laugh, "Hey babe, remember when we got that and that big ass alligator ate me", or, "Remember when that quest turned me into a wolf and I had to run through all the objectives before it wore off and I would have been standing in the middle of 25 angry mobs".....crap like that. The house and its contents was a living reminder of things I'd done in game, places I'd been, mobs I'd killed, it was all collected in one place rather than just shoved in a bank and forgotten about.
P.S. Owned a boat to, we frikkin LOVED those boats. Plop that thing in a river and float down and chill and listen to the sound of the water and birds.....not everything had to be about advancing levels or killing mobs. Sometimes just sitting there enjoying the view was all I needed.