For one dollar more, you can experience a whole other world of burger.
Here are some of my tips for the 6 dollar burger meal (you still get a boatload of fries and a drink): Sonoma style which comes with a creamy pesto sauce and pepperjack cheese. Melty with hints of garlic and a oh so moist burger. The burger with guacamole and swiss comes a close second.
The one thing to remember is cash. I would come here more often if I had dollar bills in my wallet.