You may be disappointed.
"Thank you. That is helpful.
I think we'll wait for whatever upgrade they give us. "
You are correct, the resort should upgrade you to the best available room available at check-in, however upgrades are not guaranteed. Depending on how busy the resort is you may not receive any upgrade! Friends who are plats and have stayed there in the past during high season have reported being told there were no upgrades available at check in. The only saving grace is, you probably won't be spending much time in the room anyway!
YMMV. Good luck!
Regards,
RIP...