How do I decide what to buy? I look for dusties, of course. I also respond to sales. Beyond that, I really buy the distillery and what I consider its "unique" products, distinguished primarily by mash bill, and try to mix it up.
So, for purposes of this analysis, I consider Evan Williams Black Label and Elijah Craig 12-year-old the same whiskey but Old Fitzgerald a different whiskey, even though all three are from Heaven Hill. Then I just ask, "what haven't I had for a while?" And by that, I mean what distillery/mash bill "product" haven't I had recently? It was on that basis that I recently bought a bottle of Wild Turkey 101. I know what Wild Turkey 101 tastes like, but I haven't had any recently. With Beam, Turkey and Maker's, I do have to remind myself to "check in" from time to time, even though they don't pump out a lot of new products and I'm generally pretty familiar with their lines.
Of course I also know that 12-year-old Elijah Craig is a very different expression of a Heaven Hill ryed bourbon from Evan Williams Black Label, and that's in the mix too, but at a lower priority.
Of course, in any given shopping situation you have to deal with the choices before you. At Liquor Barn last Friday, my choices were unlimited. At Jewel-Osco two weeks ago, when I got the Turkey, they were much more slim.
An illustration: I love the variety of BIB choices at Liquor Barn. Last Friday, I got JTS Brown BIB and HH 10 BIB, which are both HH ryed bourbons, but passed on the J.W. Dant and T. W. Samuels bonds they had, since they're HH ryed bourbons too.
I'm recommending this only in that if you want to be familiar with "everything" you, at a minimum, need to periodically sample every recipe from every distillery, in at least one expression.