As mentioned...if you're asking about a pts upgrade I would totally give up on that idea as it's usually only known to happen on pts on rare occassions when something has happened to the room to take it out of comission due to maintenance problems and such.
As for cash upgrades....if you go into it being happy with what you've already booked and happen to luck out then great

If you'll be devestated if you don't get an upgrade then I'd book what you want from the get go.
FWIW, We honeymooned at the GF for the first 2 nights and then moved over to POR (then Dixie landings) for the next week and had booked just a standard garden view and when they found out we were on our honeymoon, they upgraded us to a suite! To this day it is still one of the most awesome stays we've had

I don't know if it was dumb luck,the time of year and how booked (or empty) the resort was at the time, or what but we totally lucked out.
Just make sure that you'll be happy with the accommodations you do book and hopefully you'll be pleasantly surprised

That was the trip we ended up buying into
DVC too...congrats and pixie dust to you

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