A "cocktail bar" should offer great tasting, well-balanced cocktails made using quality ingredients and fresh juices but as the style of bars vary enormously...
#1 Hospitality: A warm welcome, glass of water and brief but friendly introduction to the menu.
#2 Drinks: Agree with well curated classics with bespoke specials. Some menus with only bespoke drinks may not cover everyone for more than one drink or maybe intimidating to newcomers. Also many bespoke menus don't change for awhile preventing return visits. Menus should indicate serving, strength and flavour profile, not just ingredients. Glassware and ice are very important.
#2 Drinks: Agree with well curated classics with bespoke specials. Some menus with only bespoke drinks may not cover everyone for more than one drink or maybe intimidating to newcomers. Also many bespoke menus don't change for awhile preventing return visits. Menus should indicate serving, strength and flavour profile, not just ingredients. Glassware and ice are very important.