While I don't know that I can offer much help, I am pretty sure you can change your location if it's available. It sounds like Atlantic Dance Hall might be cool and fit great with your colors and it's in the same area as Ariel's.
As for your DF's parents, we just had the weekend from **** with my DF's parents telling us the same thing AND telling us they are no longer going to pay for half of the wedding. 3 months before the wedding, and now we have to come up with $10,000!!!!!!!!!! We're FURIOUS!!!! So here is a hug because I KNOW how you feel!