I'm a fan of deco planner, but I wish it there was a Mac version. I find it easy to use and it's not cluttered with things like runtime otu and cns (I'm generally unconcerned with those things).
Decoplanner will run on a Mac under Wine. It was pretty easy to set up, but I don't remember now where I found the instructions. MultiDeco for the Mac replaced it for me.
(I used Wineskin.)