A Professional AV installer isn't going to (or shouldn't) focus on wiring your speakers. He should make an analysis of the best sized screen, appropriate speakers for the environment, room acoustics, as well as video calibration.
He should test the room acoustics and point out where the problem areas are, and suggests acoustic treatment to minimize those problems.
But before anyone says yes to such an endeavor, we would need a complete run down of the circumstance.
The size and shape of the room? (dimensions)
We need general visual assessment of the room acoustics, and how the room is laid out and constructed.
A list of the equipment that will be in the room?
Is the Room a Dedicated Home Theater, or is it a multi-purpose room? If multi-purpose ... what purpose?
I would say if you have many thousands into the room and you can find a competent installer, then that installer might be of some value.
However, if you have a typical $500 AVR and $1500 in speakers, in a converted bedroom or basement. Then I don't think you are going to be able to justify the cost. Just apply some common sense and understand your objectives, and you should be able to work it out on your own, or with the help of the forum.
Most people compromise there Surround Speakers simply because circumstance force their hand. You have to do what can be done in your room. In a very larger deep room, you could use floorstanding speakers as surrounds, but in a small room that is impossible unless you are always in the room alone.
I think I would only hire a professional if the cost of my equipment was high enough to justify the cost.
If you post some photos of the room in question, with a list of equipment, then I think many members of the forum would be willing to make helpful suggestions.
By the way ... REW... is Room Equalization Wizard
. It is free software that can analyze your room, and graphically show you where the problem areas are. It does require some additional hardware as well as a computer, but many people find the overall price very modest.
You can also search YouTube and find videos about REW
including Videos on how to set it up.
A good new AV Receiver is going to have built-in Room-EQ. But while Room-EQ can make a good room better, it simply can not make a bad room good.