In a study of two hotels in Zurich, Switzerland, researchers used price premiums and increases in occupancy rates to compare rooms within the same hotels, identical except for their views. They estimate that the hotels gained $16.34 and $4.28 million over a 20-year period from having a side with a great view, in one case a beautiful central-city riverfront and in the other a lake with a panoramic view of the Alps.
Lange, Eckart, and Peter V. Schaeffer. (2001). A comment on the market value of a room with a view. Landscape and Urban Planning 55(2), 113-120.