I forgot to mention in the OP that if I book UA on Expedia then I can get the Pheonician in Scottsdale for 7 nights at only £300 extra

. The best deal I could find for that hotel as a seperate booking was £272 per night.
So to go BA would be ~£500 +£50k + ~£1500 extra on the hotel.
Thanks to DNW for suggestion expedia holidays who I have never tried before.