A regular suitcase works just fine, you don't really even need a hard sided one, but having little wheels and a pull out handle is a good idea. I've traveled to CA and IL several times w/ my gear. Regs, Can Light, computers go in my carry-on. BPW, Turtle Fins, Booties, Wetsuit , Mask, & accessories fit in a medium sized suitcase. The wetsuit and wing help to pad everything.
I actually have a Stahlsack bag that I got several years ago that I use along w/ the suitcase. It's a regulator bag that also has a mesh gear bag attached that scrunches up and stores in an outside pocket of the reg bag. So you have a small roundish pancake bag that the regs go in. I put this is a small duffle carry-on, along w/ my other carry on gear. When I get to the destination, you can unzip the pouch on the reg bag, pull out the mesh bag, load all your gear from the suitcase and head to the dive site.