I have been platinum the last few years and my "upgrades" feel more like what I should get as a gold. I rarely get upgraded to suites but usually get something a little better than I booked, either a larger room or a better view. I'm ok with this because I know there are a lot more upgrade-eligble travelers than there are suites to go around. As for asking for upgrades via that app, I've had some luck in the past asking for upgrades that way but in recent years I usually get the whole "we can look for you at check-in" response. As a gold, you should probably be clear what type of upgrade you'd want when chatting with the hotel through the app, and ideally ask for something you could expect as a gold, which is an enhanced room and not a suite.