You're talking about a bike you want to be able to ride 2 up on, and be able to do long days in the saddle on, so you're immediately into 2+ cylinder bikes.
Small ADV bikes like the 890R, Tenere700, etc are wonderful...but they get pretty cramped with 2 people, and are a little more buzzy on those long highway jaunts. They also tend not to have as much weather protection. From what you describe, it sounds like you'd be happiest with a liter-ish bike rather than the midsize ones, and a bike that is more on the street-oriented side.
I personally thought the flat twin BMW GSs I've ridden were excellent street bikes. The telelever front end works pretty well on pavement, great weather coverage, plenty of storage, and potholes and stuff don't matter.
The yamaha super tenere is possibly one of the most reliable bikes out there and has been unchanged for years, but they are also one of the heaviest. I almost bought one, but the weight and engine character turned me off.
If you want sporty ADV, the KTM 1290s are excellent. You don't really need the off road capability of the R, plus the R is a bit taller. I've not ridden a multistrada, but I would guess they are similar. These are my favorite of the giant ADVs because they are such enthusiastic bikes/engines, but that doesn't matter to everyone. The tradeoff is they are a bit more high strung, and the styling can be polarizing.
The Africa Twin is a good bike, but its strong points don't really help for your use case unless you are interested in the optional DCT transmission.
Nothing you describe requires actual off road capability, so I wouldn't worry much about that. Any bike can go down a gravel road, and most bikes will do much better in the dirt than you'd expect if you've got somewhat treaded tires. That opens up sport touring bikes, but I have much experience with those aside from shopping for ST1100s years ago.
Personally, of the adventure bikes, I'd put a water cooled BMW GS or a 1290 towards the top of your list, leaning towards the BMW as it's got the best weather protection of the big ADVs. I'm also making some assumptions about your budget with that recommendation.