The most suitable day may be outside the historic centre: a coast day, a vineyard, a sporting event, a smaller town, a family interest or time set aside simply to breathe. It need not be the first popular excursion that appears in a search result.
A strong suggestion is one that fits the group, season, energy and onward movement. It can be a whole day, a half day, or a carefully chosen interval that gives the trip a different texture.