If you want the king of gourmet burgers go to DB bistro. The burger: foie gras and truffle in the center, wrapped around it is spare rib meat, wrapped around it top cut sirloin meat i believe....it's like 35 bucks though unless price has gone up.
I think Rare Bar & Grill could be classified as having gourmet burger options. It is reasonably priced too. I ususally get the mini burger trio. It comes with whatever the mini burger specials of the day are with cesear salad.