If you know your way around Photoshop then stick with that. You've already won half the battle. Just follow a tutorial or two and you'll be fine and figuring out all your own methods real quickly. In my opinion you are correct about Campaign Cartographer - it has quite a steep (and kind of unintuitive) learning curve. Some of those that use it can create some fantastic maps, people like Gandwarf and I think it's Cereth that is doing great stuff with the city designer but they are the exception.