Walthers Steel Mill series has been HUGELY successful. I suggest doing a series of O Scale flats of the FORD River Rouge complex. Not only could you do different sides of the plant which included multiple assembly buildings, a glass plant, a steel mill all types of sub steel mfg 
components an iconic Ford Water tower but all the tangential products Menards could do. There is / was a huge freighter dock in the middle of the plant to off load ore, coal, sand. So Lake Freighters could go with line, tugs, so many additional smalls. Cranes, gantrys conveyers, unlimited industrial options. Ford Rouge had it all.
