Wait about 3-4 years, i think, then there would be a new Starwood Property in Singapore in the form of St. Regis, located along Orchard Road, next to the Regent.

Last I heard, Starwood was also thinking of expanding the W Brand to Singapore.

As for which hotel to stay in, both hotels are top-class. If I am fortunately enough to decide between these 2 hotels, I would be in a dilemma too. But I think I would go for the Oriental, just because it is just refurbished and I have heard a lot of good things about the new property. Take a look at the following thread:

A Comparison (of some sort) between RC and Oriental:
http://www.flyertalk.com/forum/showt...=464984&page=1
A Review of the Oriental Singapore (after refurbishment):
http://www.flyertalk.com/forum/showthread.php?t=442223