While CC3 can be used to create encounter scale maps, it is really more a regional mapping software. Profantasy, the makers of CC3 have add-on apps including Dungeon Designer and City Designer, which are ideally made to create dungeon and city maps respectively. Dungeon Designer is more suited to the 1" = 5' type maps.

If you already have PS CS3, I'd say dive into the PS tutorials here at the Guild and give that a try. CS3 is more complex but offers a much wider range for the kinds of maps you're looking for.

CC3 is more a CAD app, with a steep learning curve, and in the end requires external source map objects and textures to do a nice map, that doesn't look like a typical CC3 map. YMMV.

GP