Hey Mcat!
When I read your initial post, I thought: Madeira Island, Portugal! It's nature focused, I apologise. But it's a beautiful island, you can rent a car and go around easily and it's known for it's beautiful flowers. The food is not the main attraction and it's a slow pace travel destination aimed at senior citizens. I just loved the vibe of the place.
Back on track now, I would strongly suggest Vienna. It's beautiful in terms of architecture and history and overall prettiness. It's not a massive place so you wouldn't be sitting in a car for a long time. While you rest, your DH can simply go out and walk around. They have great beers, surely they will have alcohol-free beer options too. Again, it's a beautiful city, I cannot state this enough!
I second Switzerland. Again, beautiful and magical with all that old world charm.
I have been to Czechia, Poland and Hungary and ... I would caution against these destinations in your specific situation. In these places, you will get "cute, european, history since the middle ages" charm in the main city centre, which will be great. However, outside of the cute bubble, you will get soviet architecture and communism poverty vibes. The level of customer service and general population overt happiness will also be pretty grim by north american standards. (I went with a friend to shop for her expensive wedding dress in Poland and there was zero happy or celebratory energy about it. "Here are the dresses. You like? Don't like? Chose one and come back in 10 days for the next fitting)
I have been and loved my travels there, don't get me wrong. I just think Vienna and Switzerland will give you the old-European charm with castles and royalty and history and city buzz without the depression inducing post soviet vibes. (it's a cultural thing in eastern europe, smiling to the person you're interacting with is a sign you take them for an idiot and you think you can take advantage of them).
Germany may also be a good option but I've personally only been to Oktoberfest and the only memory I have is of being drunk in a super cute fraulein dress.
I disliked Belgium intensely. Grumpy people, bad weather, nothing charming. Grey.
The Netherlands are really cool. Plenty of culture, history and design, a very cool way of life, people are open minded. Weather can be terrible, rainy, grey.
What is it that your DH disliked about London and the UK? Was it that the city was too big? Unreliable weather? People are unwelcoming?
I would caution against Rome if you're going on the assumption that food will be bad and it won't tempt you. Food is Paris can be terrible too, but still...