If you want a fat, juicy burger and a portion of fries bigger than your face, Flipside is the obvious choice.
I visited for lunch during the week, and knowing I probably wouldn't find parking in the area at lunch, I popped an uber. (I was right. Literally nowhere to park). The service inside the restaurant is fast, which I appreciated when in-between meetings. The restaurant has a hip vibe and you can't beat its fantastic location of the happening Flats.
The burger selection is HUGE. I loved the One Red Door Burger (crispy shallots, melted brie, applewood bacon aioli). That bacon ailoi is a-m-a-z-i-n-g. The "side" of French fries was also so large it required its own plate. Good stuff. They also present your burger unassembled, which is a little different for burger joints in the area. Be prepared to accept you'll be taking some leftovers home!
Bottom line: If you bring someone here, and they can't find something they love, they're just not trying hard enough. I think this is going to be a new go-to place when I have friends in the area.