In the past i used the burton wheelie gig bag, and recently I got a burton wheelie locker bag.
Both work very well. I think that a hard case is overkill unless you travel a lot and in really rough conditions. The two bags that I mention above are both padded and once you cram all your other stuff in them there's lots of additional padding.
The wheelie locker can tempt you to take too much, it holds a lot of stuff and you can wind up over the weight limit, without any effort at all on my last trip I put three boards, two sets of bindings, boots, helmet, and all my outerwear plus tuning tools in there and was over the limit but lucked out and didn't get dinged.