Considering on what we already have I'd like to request tilesets in the following architectural and decor styles:
Beaux-Arts
( The style of many old public and governance buildings having grandeur, while being practical and being imposing. A monument to progress. )
Biedermeier
( Bringing a nice mixed middle ground between the old high class pomp and low class rustical with the rise of the middle class )
Italianate
( A combination of other styles [classical, neoclassical and paladian] we get a mediterranian flair which is ditinct but still good to combine with otehr styles )
Victorian
( I guess this one is known well enough Bricks, Sandstone decor and wrought Iron. A nice way to integrate the desert style into others too )
Giyōfū
( A mix of western and japanes style buildings arising during japans rapid industrialization [Japanese-Western Eclectic Architecture])
Art-Nuveau
( Not really an architectural style but very distinct and colourful in it's way perfect to set some highlights in a build and get some great eye catchers and colours into Tilesets and furniture)
Such features will definitely increase the attractiveness of the game.