You'd be perfectly happy having an over-sized burger and a heap of fries just about anywhere, but when women go out together, they want to be in a joint where they can gawk at the interior's aesthetic. Also, preferably sip sangria, share food (which is why tapas and small plates spots are always a good idea), and talk loud enough that surrounding tables ask to be moved, usually in that order.
How to approach her: If you catch her at the bar before dinner, ask if she's eaten here before and if she knows what's good. Or, try sincerely complimenting her dress. She's probably dressed to impress (her friends) but she'll appreciate you noticing.
Just don't ever approach her at the table. That will never work.