For a drinker, the quickest bars were SpiceH20 and the Observation Lounge. There were always 2 bartenders at Spice and sometimes 3 in the OL. Unless it's packed, or there aren't many servers, we found ordering from a server was nearly as fast as ordering at the bar in the OL.
Maltings Whiskey Bar is usually fast, with less people, but we found it kind of dark and dreary, with no windows, compared to the Encore's whiskey bar.
This was last September, so YMMV.
Otherwise, completely agree with Pitzel's remarks.