I’m sort of with ken green - Adjustments may make a difference, but I don’t think they’re the only important thing (ie, my Mazda6 having fewer adjustments than a Ford Fusion SE, but being significantly more comfortable)
As for CarMama’s suggestion, local dealers are dumping all 2012 Escapes now at 20-25% off of MSRP. Some screaming deals there, if you can stand the vehicle. Seems like they’re having a hard time moving them now that the 2013s are in…
While I’m not a Volvo fan, their seats are some of the best. If you can find a new car show, they’re good for sitting in a lot of cars in a short period of time.
Hertz Car Sales (where they sell their ex-rentals) has a rent-to-buy scheme that lets you try out cars for a couple of hours for free, and also lets you rent their cars for a few days and applies the rental charge towards the purchase if you buy. They also have fixed prices, always pleasant. It might work for you. I also have serious sciatic problems, so you have my sympathy. Wish I could help more in finding the right car, but have nothing to add to what others have said, except that I find I have to change positions periodically and power seats make that much easier.