I've been told that particularly for CA, if you're planning on returning to the state, it's much better to maintain your license. CA gives you an option to maintain it as an inactive license, which only means that it's less paperwork to fill out, but it still costs the same as an active license, but it's not difficult if you want to activate the license.
I let my CA license expire a couple of years ago because I don't know if I'll ever move back to CA again. But I've heard that by letting it expire, if I want to get re-licensed it will be much more difficult to do so than if I never even had a license in the first place, because they will have to investigate why my license expired. The application process is therefore longer than even the initial application (which is already incredibly drawn out), and it's much more paperwork, and a lot more questions that have to be answered. Granted, this is only hearsay, since I have not tried to get another CA license, but if you are definitely planning on going back to CA, you should keep that in mind.
You may want to talk with someone at the CA medical board to discuss your situation to see what the pros and cons are for your options.