Regarding dancing - our Rabbi said it is prohibited to dance when there's no mechitzah regardless of being able to see girls dancing.
But very fast this discussion went from having mechitzah as a result of pressure from parents (from one or both sides) to it's origin - parents who want and will rule your life if you let them just start. Noone wants to harm the new-born couple - they only want good, but at the end very high percentage of marriages end up divorced because of someone trying to help. This is a known issue (tech words :] ), you could say a high priority bug, but there's only one way to fix it - not let it happen in the first place. And this first place is your wedding, which is the first chance for you (two) to say no to any pressure from any side as long as at least one of two is against it. If you don't let them rule you now they will not be able to rule you later, but if you let - you're in a big trouble - you showed your weakness and they will remember it and use it.
Unfortunatelly this is a main thing people overlook.
But don't try to go against one side of parents and let others put their nose in your personal business - this will not only make harm mentioned above, but also may make your and your chosson/kallah's parents enemies for their entire life which is not much of fun either.
So shortly try to avoid any 'suggestions' as much as possible when preparing to your wedding unless you ask for it yourself and beizrat HaShem you will live in peace with your spouse, parents and in-laws.