If you are already drinking flavored coffees and are interested in experimenting with the unadorned product, you might begin with one of the more distinctive single-origin coffees, particularly those that are striking in flavor yet not overpoweringly acidy: an Ethiopia Yirgacheffe, a Yemen, or a good Brazil Santos. Or try a moderately dark-roasted version of one of these coffees, and add a little cream or milk to your cup.
Or you might flavor the brewed coffee yourself. Rather than buy amaretto-flavored coffee, add a little actual amaretto or almond extract to your cup. Or try a drop or two of vanilla and a twist of orange peel.
In one of the companion volumes to this one, Home Coffee Roasting, Romance & Revival, I offer a chapter of recipes for adding completely natural flavorings to whole-bean coffee: orange zest, vanilla bean, and the like. Most people who have tried these recipes feel they produce a better flavored cup than any of the artificially flavored coffees sold by specialty outlets.
A final note of warning to those who grind their own beans: Flavored coffees are liable to ruin grinders that use burrs rather than blades to take apart the coffee. The flavoring material clings to the burrs and complicates cleaning and is almost impossible to remove completely. In other words, once you grind French vanilla, you will continue to grind French vanilla for awhile, whether you like it or not. And if you grind several flavored coffees in a row, you may begin to get a sort of combined, omnibus flavor out of your grinder no matter what you put into it. Even the little blade grinders need to be carefully cleaned after grinding a batch of flavored coffee, so as not to contaminate the next lot.