Lighthouse Some of us love lighthouses. Great view, couple of levels.
Thieves Den This might require some additions to furnishings. This would be a cave or old ruin where we have our hideout and store our "loot" (furnishings of open chests spilling gold, paintings, gem-encrusted vases, bolts of silk, silver dishware, etc.
Assassin's Nest A river-town shack? Furnishing choices could include trophy skulls mounted on plaques - from human to Bosmer and everything else, too. A "Blade wall" where a selection of knives are displayed like a gun wall.