Of the hotels I have stayed at, the following two stand out as the overall best experiences based on hotel, service, location, etc.:
Grande Bretagne
Marques de Riscal
I've had pleasant stays at the Blue Palace, Mystique, Pine Cliffs Ocean Suites, Palace Hotel, Bristol Warsaw, etc. etc. but none come close to the other two properties.
The US properties of the LC portfolio that I have stayed at have all been good with the Liberty in Boston probably being the best. I loved the US Grant from a property perspective but I probably slept the least there of any hotel I have ever stayed at due to absolutely horrible window soundproofing.