Actually, I've been married for too long for DDR to have been out when we were dating, but we've done the arcade thing since and enjoyed it a great deal.
As for whether it would work on a first date, I gave that same advice to a younger friend of mine and she reported that her date was so bad at it that he just start jumping around in circles on the dance pad, knocked her off by accident and then they had a great date after that. I mean, seriously, how could the date have gone downhill from there so neither of them had any issue with being themselves after that.
Oh, you do know that places like Dave & Busters kick minors out after a certain time on the weekends, right? So you don't have to worry about kids spilling their drink on you.