A related question may be this one: How can I do a "broad" search for flights?, but it's a quite broad question (as the title suggests haha)
Maybe the most similar question is this one: Search engine for stop over possibilites. That problem is solved by search engines like https://www.cleverlayover.com/, but it doesn't allow to enter several origins and destinations (typically cities with airports close by), or several dates.
Other search engines like https://kiwi.com/ or https://www.azair.com/ doesn't allow to enter a longer than 24 hours stopover.
The favourite solution or manual workaround so far is using azair.com to check the common (short) layover stop cities after selecting several dates and cities. Then writing down the most repeated stop cities. Then booking flights with those cities as stop overs independently.
Any search engine that does all that work automatically?
Reading comments and answers, the following should help to understand the question better:
the stopover city is not so important, but it's a good thing to have options. It's an opportunity to give a short visit to a city that didn't attract me, so I probably would visit it otherwise. Everything is variable in different levels:
- Origin airport including near airports
- Stop airport anywhere in the world
- Destination airport including near airports.