Is your credit union a member of CO-OP? this allows you to bank at any credit union in the nation that is a member. Some stuff can be challenging, like getting a loan, or getting a replacement bank card immediately. I'm living a state away from mine, with very few problems.

If you're looking for a checking account, I highly recommend Charles Schwab. They've always had excellent customer service, a pretty modern tech presence, and best of all you can use any ATM anywhere in the world without worrying about fees—they'll reimburse you for any fees charged.

Why do you have to switch off the local credit union?

The cards generally don't work overseas.

The OP wrote "leaving SF to travel around the US."

I read "SF" to mean San Francisco.

Also, I usually have better luck overseas with my credit union visa card than I do with my credit card (since I know the PIN for my checkcard).