Before OpenRocket came out, I'd do drawings in Canvas. Still use it for more complicated mechanical designs, and stuff like laying out rings and ebays that none of the rocketry programs are useful for. Could never bring myself to spend the $$$$$$$ on rocksim - there was a time when if it was maybe 1/3rd the price I would have purchased it, now I wouldn't. Always got sufficient sims with free simulators like WinRoc & RasAero - both of which can give you a quick answer without fancy drawings, unlike rocksim & openrocket. I still find RasAero to be the most accurate - I've heard some say its better than rocksim, particularly for Cd calcs & transonic flights. Now when I do rocket layout/design, I use OpenRocket - its a great program and free. Sims are with openrocket and RasAero. I also use the Cd calc in RasAero to help in flight motor characterization.
One thing I wonder about is if openrocket can be used for the simulations required as part of a class 3 waiver (P motor & larger), since it claims to do the required 6 DOF sims, like the 1 kilobuck RS PRo - can this remove one of the hurdles for such a waiver?