I have no idea what 16yo girls want out of a dinner but given that you can't drink or get into clubs I'll suggest something that's an activity as well as a meal, like korean/japanese bbq or hibachi. For korean/japanese bbq there's koreana in cambridge and gyu kaku in brookline, for hibachi there's bisuteki tokyo in cambridge. Or you could just do cheesecake factory at either the prudential mall or cambridgeside galleria - both are in nice malls so you can walk around and check out stores and get boba or something.

Not dinner but I can also suggest the laser music shows at the museum of science on fridays and saturday nights, they do beyonce, fleetwood mac, pink floyd, and radio head. It's like $8 per person and decent fun.