Well, now that I have all shop upgrades excluding the one that may be in Ryuwn, I feel that I should post my knowledge:
Togle: Go to Togle and vist the harbor (make sure this is the first thing you do). If you get the event with Yuri, that's a good sign. Afterwards, go to the shop. Keep coming to Togle (and ONLY Togle) until you get the shop upgrade (you'll know when Yuri changes her stance permanently after talking to her in the shop if you've gotten it). Yup, we all pretty much knew this one.
Ryuwn: None. After a *very* long time, I have gotten Readme to switch to a new stance. She mentions how she was looking for a book called "Scrumptious Cakes". Despite the new stance, nothing has been added to the shop. I've also gotten misc. other messages. Nothing. If you think you can prove me wrong, post it in the misc Q&A.
Torble: Chiho is a flirtatious girl, and this is to your advantage. When you go to Torble, always visit and talk to Chiho first. She'll say something along the lines of "It sure would be nice if "you" would take me on a date sometime..." eventually. Keep coming to Torble (and ONLY Torble) and getting her to say that until Chiho, too, changes her stance permanently.
Vizley: I'm surprised that so few people have this one (or so I hear). Once again, keep visiting Vizley (yes, ONLY Vizley) and talk to Laurier at the hospital (shop), make sure that's the first thing you do. Get the even with Talt to occur enough, and Laurier will then change her stance (and if you talk to her again, she says that you should ignore Talt. Sound advice).
That's exactly what I did, and now I've got all but Ryuwn (I'm working on it). Remember that the items won't appear until the next week, but just because you don't go next week doesn't mean you need to do it all again. I found that going to other areas while in the process of getting the upgrades often screws you up, which is why I say ONLY go to suchandsuch area until you get the upgrade. Oh, and, 100 fame is NOT required for any of them. The number of times you need the event to happen is usually around 3 times (that's what it was for Vizley and Torble for me). I am at rank S, but was only at rank B for Togle (fresh off of C). Also, I went in order (Togle, Torble, Vizley). You *might* have to go in order. I don't know if that will effect my chances of getting an upgrade in Ryuwn, but I'll let you know.
P.S. If you've already spoken to Chiho/Laurier first, going to the University or School is fine.
Don't be discouraged if you don't get this on your first attempt. If you've gone every chance you had for about a year, go somewhere else, completely break all rules I mention, and start there again. For the last two you may have to beat Xevion.