Check the magazine racks at your local stores, Iron Horse is one and I forget the name of the other custom builder magazine, but anyway flip through the magazines and find the type and style of motorcycle you want to build and then throw your own ideas into how you want it to look.
Welding... Nice looking welds can be weaker than cardboard and snap when you least expect it, do you want this to happen when you are doing 80mph down the freeway? Leave frame welding to the experts.