Have you tried Kiwi.com? I think they are still superior in some aspects of UI/UX than the competition. They allow you for example to select a range of dates fo

Have you tried Kiwi.com? I think they are still superior in some aspects of UI/UX than the competition. They allow you for example to select a range of dates for your departure/arrival instead of single date. They also give you ability to choose multiple departure/arrival points. And these points can be cities, regions or countries. I have not seen other websites that give you that kind of flexibility.