Parents don't get to dominate, but I do think that three hours of open bar and then transitioning to cash bar is weird. I have been to weddings with open bars and (fewer) with a cash bar, but I think if people know the open bar is limited they'll drink more then, and if you don't tell them you're opening things up to a lot of disgruntlement when it comes as a surprise.

It took me a second to realize that the LW is calling a wedding ninety minutes from the city a "destination wedding" is probably at least partly so people can get drunk and not have to drive home afterwards. Which is the responsible decision, but it presupposes a level of drinking culture that perhaps the couple getting married don't necessarily subscribe to.