The bar on 2nd floor of the Makati City Shangri-La (the name is escaping me).

The Blue Bar, Berkeley Hotel, London
The Long Bar, Sanderson Hotel, London
The Lobby Bar, One Aldwych, London

All had great vibe, great ambiance, and very well made cocktails.

At 'home' in Dubai (where almost all bars are hotel bars) I'm a big fan of Koubba at Jumeirah's Al Qasr and Bar 44 at Grosvenor House.

On the road, Pacific Bar at the Conrad in HK is a great place to unwind at the end of an evening and Glass Lounge at the Crowne Plaza in KL has a better than average range of whiskies. Unfortunately for me, my most common night-cap at the moment is a mint tea in the lounge at the Sheraton in Dammam.

There are also plenty of hotel bars which I probably wouldn't rate as great bars in isolation but which I have fond memories of for one reason or another - Le Bar at IC Le Grand in Paris and Side Bar at Wake Up in Sydney (which is a hostel bar rather than a hotel bar and a bit of a cattle market but somewhere where the thought of a cold beer makes me grin from ear to ear) being notable examples.

Illusions in the Sheraton hotel in Mahwah New Jersey.
they use to have happy hour from 4-7 even on Fridays.

beers would be in those days 4.00, today if you go to a restaurant and order a beer it cost you 4.00 now imagiane going to a hotel club where at some nights there was dancing. during happy hour beer is 4.00?

i'm going to say the 90's.