Texas and the Deep South are on my bucket list for the next time I visit the US. Unfortunately, I have only been to Florida in the immediate neighborhood, but that is its own "thing" and is quite different from the Deep South and the rest of the US, let alone Texas. I have "only" visited the western US (mostly California, where I was based for the longest time) extensively, as well as the East Coast (mostly New York State and the neighboring states).
But I think it will be difficult to top Wyoming, Washington, and California in terms of nature and landscapes. It is difficult to top Florida's beaches as well, for instance.
Hawaii is on my bucket list as well. I visited French Polynesia for my honeymoon, but Hawaii is quite unique because of its topography, its population size, the size of its islands, and the fact that it is part of the US.
In short, very few countries can compete with the US when it comes to natural beauty and diversity. If you add Alaska to the mix (another destination I would love to visit), it gets even better.
As usual, the problem is time, family obligations, professional commitments, etc. Otherwise, I would have tried to explore all 50 states by taking six to twelve months off and just going for it.