From Baroque and Classical (excluding the infamous later Beethoven sonatas, I guess), the most work in trills (including various fancy ornamentations -- say what you will about Angela Hewitt but she seems to make the most out of working the ornaments in Bach, maybe together with András Schiff).
I think anything in Bach where you can introduce a trill or any kind of flexibility in making turns, and various extended mordents and trills (I can't remember the terms) could be made into an exercise.
Not much help from me on this repertoire question, but I've been getting some pretty good mileage out of going back to five-finger work from Czerny, Op. 740 (I think it's the very first one from that set), and picking and choosing from Debussy's first étude (pr les cinq doigts) -- something about helping to remembering to use wrist rotation seems to be sinking in.
You know, that idea isn't rocket science, and I'm not suggesting your scales need work, but for me just isolating the basic movement I've done millions of times in the context of fuller LH scales and runs seems to be penetrating my skull a bit.
Then again, I missed the January scale contest, which I was thinking about getting around to doing a recording, just for fun, but didn't get around to it, so I'm just a random internet person, not claiming to be a master.
And it sounds like you're better at LH trills than me -- the repertoire I play doesn't need fingers 4-5 trills, so I don't bother to try. Anyway, I'm just talking about LH trills -- for some reason, RH trills have never been a problem (still, fingers 4-5 and simultaneous trills in the same hand aren't that strong, but, you know, all those trills in Mozart Concertos when I'm just reading through are my cue to relax and think about turning to the next page).