Thank you very much for all the thoughtful replies.

As I write I could only find ocean view rooms available on Marriott.com. How many--I have no idea. I assume it's an off-ish season because most other time/dates weren't available even 9 months ago.

I'm trying to foresee the merit in the various approaches if I need to choose just one. What's your take on the questions below?

Do you think it's wisest to choose a course and stick with it or can I mix & match? For example, let's say I take the course of emailing the GM as outlined above. After doing so, I should or should not then call plat line to request same? I think either can be followed by a call day of arrival for status of request.

The request is best with specifics or just general? e.g.
-Mr/Mrs GM you have no obligation but I would love plat upgrade to ocean view suitable for family of 4
OR
-Mr/Mrs GM you have no obligation but I would love plat upgrade?