Just for the record, I am a Low Carb Paleo Locavore, so what I consider an appropriate, healthy diet may differ from what you consider healthy.
I do some up front research about the places that I am traveling to. I like to go to restaurants that feature locally sourced foods. I identify a few choices where I think I can find foods that I would enjoy. For example, I was recently in Vancouver, BC. I checked out Cork and Fish, Go Fish, and The Twisted Fork. All of them were excellent. I try to get grass fed or pastured meats. I embrace the fat as long as the animal was raised in a healthy manner. I do the same thing when I go out locally.
If I'm on a road trip, I'll pack an ice chest and eat that before I'll go to a fast food chain. Once I reach my destination, see above. You can even find stuff that's not too terrible in an airport, although I often pack a meal when flying too.