Excellent to hear from you again, anonymous! I’m afraid that’s quite a tall order for one post, though, especially given the fact that each region is a large place with many cities and landmarks to visit. My advice would be to do some cursory research into each city and pick out which ones would interest you the most based on your preferences. Each city and town has its own atmosphere, after all, with places like Lilycove City appealing to entirely different people than Fortree or Mauville. If we knew more about you, we may be able to narrow down the list and talk about one city at a time, as I had with Goldenrod.
Also, I must admit certain developers might perhaps not be the best people to ask. Cassius, for example, is a wonderful person, but the places he typically frequents are a bit more … intense and underground than most people would enjoy. Amanita, meanwhile, is a bit too young to have a diverse set of experiences with her home region (and she hasn’t lived in Castelia for that long). Finally, Bebe … well. She’s enthusiastic, but there are times when she, too, comes up with suggestions that … perhaps should not be followed. Molayne is quite possibly the only one I can imagine would give sound advice on the matter (aside from Lanette, of course); I would have to see if he’s willing, should you be interested in any of the Alolan islands in particular.