There are still a handful of good locations out there, such as MKE, PIT, SNA, AUS, and IAD that have a decent selection... I also despise the crossover slop that the aisles have become. I'm not a Hyundai, Kia, or Nissan fan by any means, which often rules out half of the aisle for me.
I think the diversity of the aisle has also taken a hit... Where are the Ford Explorers, Miatas, Chargers, Mustang GTs, etc that used to be there? If you're going to have a premium brand like National, then at least have the premium options available to select from.
Don't get me started on the BS that I have experienced at DCA, RDU, and MDW the last few times I've been through... The aisles there are compact vehicles, which is so frustrating that a kona is an "upgrade" from a full size sedan. As others have mentioned, there's no way a Kona has the same level of class or room that a 300 did just a few years ago.
Customer service at some of those spots has gone down too, but I'll leave that hot topic for another night.