It's not about telling the boutique where you are staying, it's about letting the concierge - who has the reputation and connections in the city - set you up for success. A great concierge is essential for any top 5 Star hotel in assisting their clientele. Last time I was in New York I stayed at the Ritz-Carlton, Central Park. The concierge was outstanding and got us several excellent tables in "sold out" restaurants. If I'd gone to the restaurants and said "I'm staying at the RC Central Park" I don't believe the endings would have been the same 
Best,
NickO