Both of our "children" are on the verge of announcing their engagements. We would like to plan a trip with both couples, mid August. We've been to Bar Harbor and love Acadia but it is really crowded in August. Same for Cape Cod. We love Caribbean but not during hurricane season! Any suggestions? Four of us are on the east coast, 2 in Chicago.

Niagara Falls. Poll them to see if all have passports. Take them to Toronto for a day or 2 if all have their passports.

Montreal would be wonderful.

Somewhere along Lake Superior (Ontario, Minnesota, Wisconsin, Michigan)? Might remind you somewhat of the Bar Harbor/Acadia landscape. Would be easy enough to fly into Chicago and pick up the 2 there, or fly into Minneapolis.

Niagara on the Lake, about 10 miles outside of Niagara Falls, is beautiful and a bit more quiet than Niagara Falls. Many wineries that are fun and the downtown area is walkable. You can take a day trip to Toronto. However, as tomfuller mentioned, everyone needs a passport.