I would also go without feeding them for a week. Or, with an automatic feeder that you've tried and tested prior to leaving, in the case that you really want to let them have food during this time.
Your tanks really aren't that stocked so I wouldn't be too worried in general. I might do a water change before leaving if you really want to have your bases covered. But I wouldn't change any filter media or such to ensure a substantially present beneficial bacteria colony. But even then, I don't really think it's absolutely necessary to do a water change outside of your regular schedule. If the fish aren't getting fed, they're actually producing less nh3/4, resulting in less no2-/3-, etc etc.
If your tank is planted, you should not worry about a spike unless there is by chance equipment malfunction. If your tank isn't planted, a handy thing you could do is actually throw a handful of hornwort in there. But I still think that's overkill for a week.