The Voyager XII was an excellent bike, but no longer available new. Most of them have high mileage on them now.
For a passenger, there is no better bike on the planet than a Goldwing. It is also smooth and quiet, which should suit someone coming from a BMW. Yes, it is a bit like a 2 wheeled car (though not an Accord, or Camry, the most boring cars in the world) but that is what it takes for long trips with a lot of luggage and a passenger. The 1800s handle very well. Only things I don't like about them are the chain cam drive (used to be belts) and the valves that have to be adjusted (the 1200 and 1500 has hydraulic valves). The ride is as close to an early '70s Cadillac as you are going to get.
2002 Vulcan 750, 2001 XT225
2008 Vino 125, 2009 Genuine Stella
2012 Zuma 125, 1980 Puch Newport moped