A killer feature for me is combining floating windows with "zellij run". It allows you to run a command but also re-run the command by pressing enter.
zellij run --floating -- date
This will open a new floating window with the result of the command (`date` in this case) and pressing enter will run it again. I use it for running tests (make some changes, show floating windows, press enter). Depending on your OS you might already have shell aliases such as zrf (run floating) or zr.