Okay, YOU got it but RIM and many others do NOT. They see things the way RIM set this up or have learned to adapt.
I think your last example, calling another TZ is the most problematic.
I think the way to not deal with the appts getting reset is to "fool" the BB. Don't use TZ at all, Live in Seattle, set the initial TZ and the clock. Go to NY, just set the clock and don't fool with the TZ. I believe appts will NOT be moved if you only change the clock and don't change the TZ. So, while in Seattle, you set a lunch appt for 1pm for your NY appt. Just set to 1pm. Now arrive at 9am in NY. Set the clock to the 3 hour difference and go to lunch at 1pm (the appt apparently does not change when you change the clock).
I don't travel much so it is only a sometimes issue. I am use to phones that DID change the time as you arrived in another TZ. I've kind of gotten used to the BB but don't set that many "foreign" appts. I think when I do go to Europe this summer, I will set flight times MY WAY which is to set the time but for the day before, set another appt "Flight tomorrow 11:20am local time"