How can asking folks if having them at both locations on the same day as opposed to each location on different days settle anything when there are probably several folks who can only make it to one of the two locations and only on one particular day. and those people can only speak for themselves. Seems you forgot folks in that situation.
Pretty sure option 1 & 2 cover them.... as well as 3 & 4. All 4 give everyone the option for what date & area works best for them. What you worried about any way your retired