Lazy Man and Money discusses frugal bar keeping. I find it interesting and want to to add to it.
I spend extra on sipping booze and less on mixing booze. In fact, I would consider it quite uncouth if you asked for me to mix up a glass of XO & coke, in fact, I probably would flat out refuse to do so. At best, I would pour in the Aristocrat and mix the coke. Same too with any bourbon starting at Jim Beam level and going up (FYI, I don’t much care for Jack Daniels (which btw is technically not a bourbon) so I wouldn’t have it on hand). I have a bottle of Canadian Club on hand (a gift) but have not opened it up yet, I should do that tonight.
I agree with the assessment of Gins - that is Gordons for mixers & Tanqueray for sipping gin (i.e. martinis). I never could stand martinis until a friend said you need to have good gin for those, makes sense.
Vodka I only drink as a mixer so cheap vodka works for me.
I don’t drink rum a whole lot and usually straight up when I do. I have a couple of bottles of Tanduay and one of Meyers. I am not a real rum connoisseur.
Brandy is one class of liquor I try to have a mixing bottle and a sipping bottle. I look for VSOP (or better) of any brand and inexpensive for mixing.
Other liquors I like to have on hand - mainly peppermint schnapps, but I should also think of Jaegermeister & blackberry brandy.
As far as wines go, I like Ravenswood & Boggle, but usually have a big bottle of inexpensive cab around for sipping & cooking. Beer?