There used to be a tool called: "Campaign Cartographer". It's intended use was for tabletop game campaigns, like Dungeons and Dragons, Warhammer, etc.
This one was rather costly the last time I looked at it (which is easily 8 years ago) but it was a CAD program with a lot of libraries for terrain, their associated vegetation and also habitation. All to be used at your own discretion.
It is good to see that the software survived all this time, it has expanded quite a lot(!)...the mapmaker alone is 45 USD but if you want "the whole shebang" it will cost 537 USD. The package deal is way overkill for your intends and purposes.
Actually I should thank you for a trip to memory lane when researching this piece of software :)
-Shades
I own CC3 Pro and I can tell you it is AWESOMENESS incarnate.you can make any maptype you want from topographical to star maps, floor plans to zone planning to street level. you can even make your own "symbols". the rub: has a steep steep learning curve to get good results.
How ever the company is FANTASTIC about communicating and helping the users. The dev's are all over the mailing lists asking for improvements that we need or helping us figure out how to reach a goal. Its a commercial version of DC almost hehehe