You have three options.
1. Follow Eric's advice and buy two plans depending on where you are living.
2. Buy a plan with out-of-network benefits. Use mail-order pharmacy for the drug benefits which will ship almost anywhere. The out of network benefits tend to be more expensive, but having two plans can be expensive, too, if you have to meet two annual deductibles a year.
3. Buy a plan from a larger insurer (United Healthcare, some of the bigger Blues) with a nationwide provider network. These can be hard to find, and they've been shrinking in recent years as insurance companies put more pressure on thinner provider networks to control costs.
If it were me, I'd go with option 2.