If you make it to the Seattle area, you are more than welcome to RON at our place in Woodinville and fire up my Ottaway. Only have 500’ of track, but if you go around 10 times, it’s a mile long run.
Something to consider, is to take in a couple of live steam 12” and 15” gauge RR’s along your route. These might be interesting to visit: (most all are clubs, except for one or two commercial operations):
The Wabash, Frisco and Pacific is in Glencoe, Missouri, NE Kansas. 12 locomotives, scheduled weekend service. All volunteer, live steam club operation. Largest collection of operating 12” gauge locomotives in the world, I think.
Also in NE Kansas, you could visit the C&H Railroad, home to four 12” gauge Ottaway’s running on a mile of track.
Once you arrive in Arizona, in addition to Maricopa Live Steamers, there is a second 7.5” ga Scottsdale live steam club and 15” gauge RR at the Scottsdale Railroad Park in Pheonix.
Going further westward, to Southern California (likely you already know this one), Joshua Tree has both 15” ga and 7.5” ga railroads.
There are actually 4 Park gauge RR’s in the Bay Area - 15” ga Redwood Valley RR in Tilden Park, overlooking Oakland in the East Bay, and an original 1904 19” gauge original Cagney RR at the San Francisco Zoo. This loco is only one of two surviving 19” Cagney’s left in the world. The Golden gate live steamers is located immediately adjacent to the Redwood Valley ROW. In fact you walk under a 15” ga trestle to get to the Live Steam loading area.
Also I really enjoy visiting the 1/3 rd scale, 19” Swanton Pacific RR, located about 15 miles north of Santa Cruz, outside of Davenport, on the Pacific Coast Hiway. Swanton RR is a non profit, all volunteer preservation RR, that consists of the locos and rolling stock from the 1915 panama-Pacific Exposition, Overfair Railway very well maintained and a marvelous place to visit up in the hills above the Pacific Ocean. They have a roundhouse, maintenance shop, and four locos, plus a RR crane that you can explore. I think you could overnight there in the campground with prior coordination. You can drive down the coast from the SF Zoo RR to Davenport in about an hour or so. Very scenic, classic SF coast road.
The other two Park Guage RR’s are Billy Jones Wildcat RR in San Jose, and Traintown, in downtown Sonoma- heart of Cal wine Country.
Also, the Cal State RR Museum, in Old Town, Sacramento is absolutely worth a must visit. Close to Sac Live Steamers, right on the Sacramento River, with great food in numerous Old Town Original preserved gold rush Main Street two story buildings, with boccu ice cream parlors. Afterwards , heading north to Oregon, you could stop at The Folsom Valley Railroad, a nice 12” gauge scheduled service with two steam engines running on a 3/4 mile track in a public park in Folsom. One of them is Eric Thompson’s original 12” Cricket.
Oregon has 5 live steam clubs, plus Train Mountain. If you time it right you could be there for one of the TM monthly meets. 3-5 days of RR fun over 30 miles of track with maybe up to 100 other locomotives. Unbelievable.
Heading on up North, On I-5 there are two live steam clubs in Washington: Kitsap Live Steamers at Port Orchard, and Skykomish Live Steamers right in the little town of skykomish, at the crest of the Cascades, along Hiway 2, heading east to Spokane, Idaho, Montana, etc. this could be your turning point heading back east towards Glacier Park and Yellowstone. In fact, Hiway 2 basically follows the old Great Northern RR route to Glacier Park and onwards to Milwaukee.
If you visit KLS in Port Orchard, you could easily drive a short loop of 200 miles or so, round trip, north up the Kitsap Peninsula to visit the Olympic National Park headquartered at Port Angeles, then take the Blackball ferry across Straits of Juan De Fuca to Victoria, BC, back across to Vancouver and south through Bellingham at the border. I say this, because Victoria is home to a very nice Live Steam club just outside of town. Supberb layout, well worth a visit. Victoria is an easy weekend holiday from Seattle area and KLS members enjoy a lot of interaction and support from the Victoria Model engineering club when we visit. Vancouver also has a very nice live steam club. You can then circle around and drive down through Bellingham and on south about 50 miles to pick up Hiway 2 heading eastward through Skykomish Pass and eastwards to Glacier Park and Yellowstone.
Ok, maybe more than you bargained for! But once you make the Pass it’s literally, all downhill to Colorado and The Dakota’s. There’s lots of live steam activity on the upper left coast!