First, a big thank you for everyone's suggestions. I've now done a ton of homework, and we're ready to book the trip in Sept 2023. Except that I haven't fully decided which cruise line
One issue, that I was frankly overlooking but my very wise DW keeps bringing up, is that I'm slightly claustrophobic. She reminds me that when we did 4 days on the Yangtze 23 years ago, we really, really didn't like our original (cramped) cabin which we spent the first night in. Fortunately, we were able to do an on-the-spot upgrade to a huge suite, that included a living room, wet bar, separate bedroom, and bathroom. As she reminds me, most of the passengers we talked to grumbled about the accommodations and consequently didn't enjoy themselves, while we had a splendid time. So it's worthwhile to get a big enough room. Some of the lines (e.g. Uniworld, which I otherwise really like), have standard rooms that are only 150 sq ft. Nope, cannot do - I don't care how little time I spend in the room, it's a no-go. I'd like at least 250 sq ft.
So here's our candidates. I'm strongly leaning toward Viking, despite the warning (since verified) that they need payment almost a year in advance.
Viking, Grand European Tour, 15 days, late fall. I've put a 72 hour hold on a Veranda Suite, which is the next smaller category down from the Explorer Suite. It's mid-ships, so shouldn't suffer from the noise problem. 275 sq ft. I'm really attracted to their air promotion, in which we can upgrade to business class for $1999 per person (despite what I told VacationForever). A friend is going business to Sicily next week, and warned that his business fare was almost $10K.
Avalon, Magnificent Rivers of Europe, 16 days, late fall. Royal Suite, 300 sq ft (their biggest cabin). I really like the vibe from Avalon, which has bicycles on-board, exercise facilities, and typically a younger crowd. The hangup is that their air promo ($399 right now) is economy only. I can book air separately without that promo, but prices for business class air scare me, and make this a much more expensive option. Unless we settle for coach class air; will discuss with DW, but this is a special trip and would like business.
Uniworld, European Jewels, 16 days, late fall. But their biggest suite, which is only 214 sq ft, is sold out for all dates that work for us. We can only get the 151 sq ft rooms. Uh-uh, sorry, no, nyet, nein; despite the fact we can get good discounts via Costco.
I welcome any further comments. Thanks again for the helpful comments.