Hey, Radagast, here are a few thoughts, for the two cents they're worth:
1) The new, hybrid-only Siennas are sure to last basically forever. They're also, IMO, terrible. DW and I took one for a test drive a few months back. I really, really wanted it to be amazing, with Toyota's hybrid tech and reliability. Unfortunately, from what we saw, it's a massive step backwards in practicality, compared to previous generations. The second row seats are not removable for hauling 4x8 goods. Well, they *can* be removed, but that requires a socket set and will leave you with an airbag warning light. The 8th seat (2nd row, center seat) has a cushion so thin and soft that you can feel the seat frame through it. The rear bench seat is awful--the front corners of the bench are cut off in order to allow the seat to fold into the rear cargo floor, and the head rests are supremely uncomfortable. The ma-HOO-sive center console eliminates nearly all the utility of that precious space between the front seats, the arm rests on the front seats can't be flipped up, and the dash looks like they let the art students design it instead of soccer moms and engineers. Basically, it's a minivan that tries its best to act like a 4-seat SUV. Or maybe it's the other way around?
2) Now is a terrible time to car shop. We're in the market for a new-to-us minivan, and have been, for the last year. The global chip shortage looks to be loosening its grip over the next 6 months, so that may help your wife delay her gratification just a bit longer.
3) If it's to be brand new, can you rent one of each model you're considering, for a week at a time, to make sure DW gets what she wants?
4) If it has to be a luxury SUV, get a Lexus.