These bourbons are aged in french oak which have been charred. This
imparts the smoky vanilla flavors that these premium bourbons have.
However, Knob Creek, et cetera, have nothing to envy.
I had the pleasure of visiting Makers Mark in Kentucky; it's good, but
not up to par with the premium ones.
I don't recall Makers Mark having a "premium" brand, and always wondered
why they don't produce one.
Cigar Aficionado had an excellent review on bourbons years ago.
Richard
notbob wrote:
On 2003-12-06, Blair P Houghton wrote:
But this Wild Turkey is gorgeous.
Wild Turkey is one of the great American bourbons. It blows those
other premium bourbons (Knob Creek, Basil Hayden, etc) out of the
water. Single-barrel WT (Rare Breed) is my favorite of all whiskeys.
I haven't tried the rye yet, but recall a website that gave it
surprisingly high marks. Maybe I'll try a bottle for Xmas. 
nb