Do you like command line interfaces? If so I'd highly recommend Rhino. Any CAD suite is going to have a learning curve to it, but Rhino is as intuitive as any you'll find, while being incredibly powerful in it's features. It has a demo version (with limited save capability) so you can dip your toes in.

There's something great about having the names for things be their commands: you want a line? Just type "line".