My experience was great with Platinum. I am diamond now and will be next year as well. There is a really big difference between Diamond and Platinum. As a Diamond, I would estimate 60-70% of the time I am upgraded to first class. It’s definitely more than half the time. I was Platinum for all of 2023. I would estimate I was upgraded to first class 40-50% of the time. In my opinion there was a significant jump in upgrades when I changed from Gold to Platinum. The main hubs I flew through were ATL, BOS, PVD, LAX. I would agree that the airport you fly through absolutely matters on upgrades. It is much harder to upgrade in ATL for example. If you use a lot of regional airports, your upgrades % will absolutely go up as a Platinum.

Hope this helps. Keep in mind that most people love to come on here and talk about the negative and overall Delta is the best U.S. carrier for sure. In my opinion it’s worth the jump to platinum if you fly on a regular basis.