Staying in a castle can fulfill a number of different fantasies. There's the princess fantasy. The extraordinary wealth fantasy. The mead-drinking fantasy. And my personal favorite, the ghost-hunting/mystery-solving fantasy. (If you can think of others send them along.)
Castle Venlaw, not far outside of Edinburgh, fulfills the extraordinary wealth fantasy or perhaps the princess fantasy. Built in 1742, the gorgeous stone castle was never a castle in the practical sense. Built to look like a storybook castle, it always served as a country getaway for the folks lucky enough to own it. Currently it has twelve rooms and a lovely and cozy library bar. The rooms have everything you'd want for a romantic weekend - four poster beds, etc.