Most hotels don't put their specialty suites into reservation systems; they are sold by the hotel directly. Only the "ordinary" suites (like 2 regular rooms) go into the reservation systems for the most part. So, if you are looking for a true luxury suite, pick the hotel and call directly; prices are negotiable based on supply/demand, but it won't be cheap. If you are trying to search for a priceline suite deal, then forget it for European luxury hotels. Finally some of the US chains such as St. Regis will have some of their suites online, but the pricing is usually higher than can be gotten directly.