Don't even consider Four Seasons in LA... frightful, both of them. I think you would be very comfortable at Hotel Bel Air. I wouldn't for settle anything less than Dorchester there... best hospitality in SoCal.
I suspect you won't be exactly wow'ed by the Spa at Hotel Bel Air, knowing you love great facilities. Actually it's tough to find anything world class in LA when it comes to wellness.
Having said that, Hotel Bel Air is one of my favorite hotels worldwide.