How about planning and creating some classic American Iron in Steam. Such as U.P 844, 4014, 3985, Nickel-plate 765 , Pere Marquette 1225, L & N 152, Southern R.R C&O 2716, 614 , 2101 N & W 611, 1218 just throwing those out there.
Steam era routes would be fantastic. Here are a few of my ideas: -NYC Water Level Route (well, part of it anyway) with Hudsons, Niagaras, and Mowhawks -PRR Horseshoe Curve or another line with M1a/M1b Mountains, T1 (and/or S1, Q1, and Q2) Duplexes, H10 Consolidations, J1 2-10-4s, the S2 Turbine, K4 Pacifics, B6sb 0-6-0s, etc. -N&W RR route with J-Class 4-8-4, A-Class 2-6-6-4, and Y6-Class 2-8-8-2 -Sherman Hill with Big Boys, Challengers, FEFs, and 4-12-2s -SP Tehachapi or Coast Line with GS-Class 4-8-4s, Cab Forwards, AC9 2-8-8-4s, etc. -Too bad we can't get ATSF. I would love ATSF 4-8-4s (#3751 and others), 3400-Class Hudsons (including the Blue Goose), and 2-10-4 Texas locos. -Milwaukee Road with A-Class 4-4-2s and F7-Class 4-6-4s on the Hiawatha -All the above steam loco ideas are fantastic, too.