Austria
 

I am Starwoods Platimun and Hilton Diamond. What are the best properties in Vienna and Salzburg.

Hi!
In Vienna i would prefer the Starwood Hotels. Hotel Imperial and Hotel Bristol are top of the list. Both absolutely in the center on the main boulevard "Ringstasse" and the interior is classic. Hotel Bristol is just next to the state opera. Le Meridien just opened 2 or 3 years ago and is also close to the opera if you like design hotels. In my opinion the Vienneses Hilton cannot beat location and interior of the starwoods.
In Salzburg Goldener Hirsch is to prefer against the regular Sheraton. It is unique: small, cosy, and at the main pedestrian zone.
I hope I was abler to help you with your decision.

I agree with magmax on all counts, and would only add that, to me, the main difference between the Imperial and the Bristol (about three blocks apart, on opposite sides of the same street) is that the rooms at the Imperial are decorated in an over-the-top rococo splendor, while the Bristol is more restrained (but still luxurious feeling). For that reason (and because of the across from the Staatsoper location) I've always stayed at the Bristol. If you search in the Starwood forum, I think you'll find some good reports about Platinum upgrades, including at least one Plat who was placed in the Prince of Wales Suite :)

Just was at the Bristol last month. Much better rates than the other hotel mentioned and received upgrade to the top floor suites with small balcony.
Very friendly, helpful staff -- highly recommended.