Having ridden both (several times), I would give the edge to the feather River, especially in a "Real" dome.

It is much more open, with its views of rugged river rapids alternating with deep water; whereas closeup trees block the view on Donner much of the way, especially westbound, west of Immigrant Gap.

On the other hand, the view of Donner Lake east of the summit and down through the Horseshoe is "Spectabulous", especially in the snow! But you just can't beat the view from the CZ Dome in the Sierra Valley on a cold snow covered moonlit winter evening - breath taking - awesome indeed.

Perhaps, Donner would have measured up equally in my experience, if it too had real domes - the kind where you sit high enough into it to easily see forward (and all around). Such domes were pretty rare on SP trains. And Amtrak's full length domes and "SightSeer Lounges" just don't even begin to hold a candle to the bubble domes of the original California Zephyr.

Now here's a thought - "Loop Trains" - Up one route to overnight at Reno, back the other - with domes of course. The old WP Reno Branch would need a lot of upgrade work - and that part of the route would still be slow. But who on a train dedicated to sight seeing would care. Now what a weekend package that would be!

Perhaps one of these days. . . . .

OPB