I currently use a credit union located 700 miles from where I live. So, I'm effectively "branchless." I've been doing this for 4 years now, so I can say it works fairly well. The main drawback is having to pay ATM fees, but I don't use ATMs that much--I tend to debit as much as possible.
I'm surprised to hear your CU doesn't allow international ATM usage. Mine does.
I'd say just look up online reviews of any bank/credit union you're thinking of trying. Any of the big ones will probably be fine, in any case.