Hey Altreg01... Fellow D2 veteran here as well. I started D3 pretty casual.. took a break and started up right before Season 2 ladder began.. I gave it a shot. From my experience, playing the season ladders has added quite a bit of enjoyment. It rekindled a bit of that fire I had back in the D2 days. From what I've read and what I have seen on the PTR, the next season, season 4, and the patch that will go with it, 2.3, are going to be pretty great. There are a lot of things going on with this patch that make the game easy to get into and have a lot of fun with. I plan on running the ladders. Granted, I am no top tier player at all.. But its fun to get onto the top 1000 ladder and try to have your name up there somewhere when the season ends and the ladder becomes permanent.
If you are going to play HC for season 3, which I was thinking of doing also, (I've been wanting to play HC since D2 and never had the stones to go through with it lol) I would suggest going with a high utility class that you think you can have fun with and go at it. No matter what you decide to do, gluck and have fun!