What kind of people are you looking to serve? Younger, older, male, female.. etc.
I tried to put together a well-stocked bar awhile back. I drink rum almost exclusively, but I wanted to serve my friends well. I quickly found out that 99% of the people who came to the house drank either fruity mixed drinks, beer, or wine. My Dad is the only Scotch drinker I know, a few people will drink rum, bourbon or whiskey straight, only an occasional gin and tonic, and tequila was only necessary for margaritas. But vodka is crucial, all the popular mixed drinks seemed to be vodka recipes, the more 'flavor-less' the better. Also high on the list, especially for the women, is coconut rum.
That meant mixers were pretty important, at least for my party crowd. Amaretto, triple sec, blue and orange curacao, peach schnapps, banana liquer, irish creme, chocolate liquer (Godiva is great), blackberry brandy are all well used in my house. I also try to keep lime juice, orange juice, pineapple juice, coconut cream, and cranberry juice in the house. Club soda in the summer time for mojitos (along with fresh mint growing in the backyard), tonic in the winter for gin and tonics. I don't mess with garnishes or fancy glassware, too much trouble, not enough appreciation, at least in my crowd.
I'd suggest take a close look at who you'll end up serving, and try to adjust for their tastes. No sense in stocking single malt scotches if they're just going to sit on a shelf for 3 yrs. If they really do have such a broad and varied taste to cover all the liquors, then I'm envious of your friends!
