I think it would be nice to be able to more easily reorder fields that you're joining by in the Join tool.
For example, I have already joined by CASS_Address and CASS_City. After I did this, I realized I wanted to go back and join on Name, too, and I want that to be first. How the tool is configured now, if I want Name to be first, I must redo all of the drop downs. I would like to be able to add Name to the next set of open drop downs then use some arrow buttons to be able to move them up in the order (similar to the Summarize tool).