As far as models go, if you want to see a bit of history - there's a little museum in Edmonds, WA a bit north of Seattle that has one of the layouts that used to be at the Pacific Fast Mail offices before they became condos. It's a mix of dual gauge and has a bit of Colorado NG to it.
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www.historicedmonds.org]
Chehalis & Centralia and as well as Mt. Rainier are both good options if you need your steam fix. Northwest Railway Museum is a lot closer to Seattle itself than either of those, but Mt. Rainier is close by the mountain itself - very close to Paradise on Mt. Rainier which is where most hikers start from and definitely worth a drive up to to see the sights (~5,000 ft elevation I want to say).
Feel free to shoot me a PM if you want any recommendations for anything else local, moved back to Seattle post graduation / CRRM to work for BNSF.
Mark Huber
Hyce on YouTube