cement pond,
Salt levels and chlorine levels are easily measurable in pool water. Ozone is not easily measurable. Both are effective sanitizers. I believe Del Ozone makes a combo unit.
I always like to use sanitizers that allow me to measure the amount that is in the water.

IMO the spa should be located where it's most convenient and efficient. Deep or shallow end doesn't matter. Good luck.

Cement pond,
Our pool is going to be about the same size, 14 x 32 with
an 18" raised 7' spa in the deep end. I think it's all a matter of preferance and most logical for each individual.
They should also take into account how far the spa will be from the pump, since a longer distance would require the pump to push the water farther. That would mean less jet action at the spa.
I was considering going with the Paramount ozone system
with Nature2 mineral and Rainbow chlorinator. But after some research decided against it because the ozone only last a few seconds in a pool, which is why you need the back up of the chlorinator. Ozone only kills certain bacterias and Nature 2 takes care of the rest. But with the Nature2 you have to change the cartridge every 6 months at a cost of $70 each. Also have to maintain the chlorinator with tablets and they have a tendacy to clog up.
I opted for the SWG system because of the ease and fairly low mainteance of it. Neighbors and friends who have SWG
highly recommended it. One has been using SWG for ten years and has had no problems with it.
It cost around $500 to replace it about every 5 years, but I think the lower maintenance out weighs the cost.
Well thats my 2 cents worth. I'm sure other people have different opinions.
Hope this helps,
Funh20

Ozone has no residual, so your friend will still need some sort of sanitizer especially during heavy use.

The spa should be placed where it is most convient to the homeowner and as close to the equipment as you can place it.

Ozone is the most AWESOME sanitizer of them all.

However to use it as your only form of disinfecting a full size pool you'll need a commercial/industrial grade Corona Discharge Ozonator.
This will cost multiple 1000 dollar bills, and the need to run your pool on a high speed. You must hit a minimum of 3 turns per day and 4 to 5 are preferred. In addition you'll be utilizing another chemical (sodium bromide) to best activate the ozone. Together they form sort of really badass sanitizing acid that blows away any other form of disinfecting. I don't know how true it is but I've heard it's like 50 times stronger and 5000 times faster than chlorine. This is probably bogus information from the mfg's rep.
I'm no fan of the residential grade ozone generators because the manufacturer doesn't point out the entire truth of the system, how it functions in amount of ozone generated, and how it can only be used a a support sanitizer.
My suggestion is to go with the SWG or chlorinated tablets as the primary and add on the Ozonator as a secondary if they choose to.

Don't be fooled about what folks may say about the Ozone generators. They're ABSOLUTELY THE BEST, especially when utilized with Sodium Bromide. Those who bellyache about them just got sucked up by some hype and had a totally mis-spec'd system for their application.

See ya,
Kelly

Cement Pond,
You can't go wrong with either choice. Ozone or SWG will make your pool very low maintenance. This has been a long running debate in this forum about which is better. IMO, I say the poll forum is split heavily down the middle for either system.
I have a ozone system and I love it. Of course you can't measure residual ozone, but there is no need to. Its either working or its not by the light being on. I work in a chemical plant with a commercial water purification system and they have a ozone system connected and our water stays pristine and clear. Just like my current pool. Of course you will a need a backup chlorinator because ozone breaks down chlorine, so your levels will always be around 1ppm or less. Plus its cool to see the bubbles come out of the pool jets. Your pool will have this champagne bubble effect at nite when the lights are on.
But with an SWG, its no different either. You will need to either increase or decrease the SWG on days of heavy rain and possibly shock your pool also. Also you will need to keep bags of salt on hand and walk around the pool pouring salt into your pool. So if your thinking its totally trouble -free, sorry but that's just not the case. You will have to carry bags out to the pool to "salt" the pool down. So this is where it just comes down to convenience. I went with ozone because of PB's saying they will not install SWG's if you have a waterfall structure. Now when a PB misses an opportunity to sell you something, I have to take notice at that. Here in the Pearland area, a lot of them are getting away from SWG's because they are having to come out and make repairs from the effect of the SWG's on water structures. But that may be just certain builders. So I decided not to risk it. I know with my ozonator I use very little chlorine and I have not had any algae or water problems yet. But I have only had my pool for three months and its cold right now. But the days we did swim in it, not one problem occurred. And I was very leary about getting a pool due to a lot of maintenance. This has been a very trouble-free pool.
So good luck. As for the location of the spa. It does come down to looks. Make sure they mark it out properly. When my PB marked my pool out on the ground, we had to go back to the drawing board, because I did not like the way it looked. Don't have your PB, just throw some stakes out. Have them use the orange or white paint and mark it out. If you have a two story, go up top and look at it from above. It will give you a clear perspective of what your getting. Walk it out numerous times and ask yourself, do you want to walk to the deep end to get into your spa? For safety reasons, I would want it in the shallow end. But that's just me.
Good Luck.