In general I use graph paper for quickie designing or playing with random ideas.
I do have EQ7 and use it more for determining fabric amounts, playing with squares that might work together, and things like that.
At the moment I'm designing a quilt more or less on the fly. Playing with rounds of squares and seeing if I like the result or not. So far I've discarded more ideas than I've used. Lol! Most of them will end up being used later, just not in the spot I originally considered.