The user adds the home location of people in the group
Then configures the maximum distance/time, the type of amenity to meet at (pub, cafe, etc)
Then submits, getting back isochrones around each starting location. Where the isochrones overlap and amenities are available, show those as possible meeting spots "equidistant" (but for time) from everyone
https://a-b-street.github.io/15m/ is the layout I use often -- left sidebar, right map