Some things from my build. I don't know about Oklahoma, but here in Tucson some of the subs do 90% of the pools here, so it is really, do you like the equipment, design and price. For the most part different builders here used the exact same subcontractors. Unless the PB is a crook, they are all very similar to deal with. I had one built and had four neighbors build in the last two years. The problems we had, they had too, honestly.
And, for a spa. The most intelligent thing I did is buy a detached portable spa. Less than half the price, very comfortable and cheap to heat even in the winter. Heats up MUCH faster too. The only real advantage to a built in spa is if you entertain a lot. They are great for parties whereas a portable spa is not. But for everyday use, the portable spas are much better.
That is a huge pool and your quotes are reasonable for that. Remember one other thing, a pool twice the size is almost twice the cost to maintain. Make sure you really want and need a pool that big.
Hope it all goes well for you. It's an adventure, that is for sure.