Texas and Washington are good schools with good graduate programmes, but they are state schools with huge numbers of undergraduates, and are much less academically competitive than some of the schools you mentioned. They are better for a good social scene and so on though.
If there are academic criteria other than going to UCL to get into the programmes at Caltech, Chicago and JHU, then you would be passing up an opportunity by going to a state school. However, all of those three are very intense and do not have good social scenes. In terms of competitiveness of admission Caltech > Chicago > JHU.
Caltech has the highest high school test scores of any US school, and is significantly harder than any UK school for undergraduate. It's chemistry PhD programme is ranked #2 after Harvard. If you think you can handle it, it is the best choice academically. I don't know much about Chicago, but don't have a good opinion of it.
I went to JHU, and would not recommend it based on my experience. However, it is also a phenomenal school. It was modeled on Heidelberg, and is closer to a European university. It is very intense, and the faculty tend to be old school tough. It also has huge numbers of premeds who will very concerned about grades. You will run into a lot of premeds in chemistry at any of the schools you are considering though.