In my opinion:
Noteworthy
Four Seasons George V Paris
Visited for afternoon tea. Beautiful property. Refined service.
Four Seasons Istanbul at the Bosphorus
Was room guest. Very beautiful property with Bosphorus views, though a taxi ride away from the city centre. Fantastic pool and spa facilities. Outdoor patio and pool area have marble floors! Wonderful variety and service at breakfast. Standard rooms are rather bland. Expensive rooms are much more impressive.
Four Seasons Florence
Was restaurant guest (Sunday brunch). Very beautiful property and interiors. Fantastic brunch and good value for the quality. Peaceful setting, but a walk from the city centre.
Four Seasons Gresham Palace Budapest
Was room guest. Very beautiful property in a historical building. Good value for the quality (a reflection of the location).
Very good but not noteworthy
Four Seasons Park Lane London
Dined at the Italian restaurant - good but not particularly memorable. Used the spa - beautiful views from the 10th floor, excellent treatments, fantastic service.
Four Seasons Istanbul at Sultanahmet
Dined there. Ideal location. Historical building. Somewhat dated hard product at that time.
Just good
Four Seasons Seattle
Went for drinks. Good service. Property is rather corporate-bland.
No intention to try
Four Seasons Vancouver
I looked across from Rosewood Georgia