I started out in that weight range and also thought steel was the best choice, but remember even strong steel bends and can crack! I cracked one myself. Of course steel *CAN* be made strong enough, but I don't know any makers who use thick enough steel to support someone as big as I was. I've had better luck with the Kona Hoss extra strong alloy frame.
I had spoke problems with the rear wheel until I found a guy who actually knew how to build them. I didn't even have to go to 36 hub, he put on a better rim and knew how to set up the spokes properly. I haven't had a single ping since, going on a year and a half.