I'm not sure what the community thinks about Inkarnate, but it just might be the tool you're looking for. You can make pretty rudimentary maps, or, if you have the time and persistence, you can make rather detailed landscapes enough to satisfy yourself with. From a DM to another DM I can promise you one thing. If you put time into it and love your map then your players will love it 10x more.

Link: http://inkarnate.com/

It's in beta, so just be aware of that before going into it. Here's an example of what I managed to make. You could probably make something much better than I.

Oria.jpg