I plan on staying at the Four Seasons resort in Maui in August. What sets them apart from all the rest on this island? Is there any way to get even the slightest discount on their rooms, be it Maui or anywhere there's a Four Seasons?

Well, not all Four Seasons hotels are created equal. The Four Seasons Houston and Seattle come to mind. Nice places, but mostly business hotels, for which weekend deals can be had.
The Four Seasons resorts, on the other hand, are typically a cut above whatever local competition exists. Service is top notch at all FS hotels I've been to, city or resort. The resorts are usually in prime locations.

But to answer your question as to what sets the FS Maui apart....it's that virtually everything is done right. Everything works virtually all the time, if anything is flawed it will be fixed pronto with profuse apologies, everything is clean and well maintained to the nth degree, service and attitude of staff are always respectful and courteous, materials are always high end (linens, furniture, toiletries, towels etc), restaurants are highly dependable, the atmosphere is virtually always refined and relaxing....and on and on.
Why does this matter? Because even nicer chains like Westin and Hyatt etc still have their flaws. They may get it right 85% of the time, but occasionally there's the staffer with attitude, or lazy help, or a mess in the room when you check in, or mediocre food on site, or cheap towels, or whatever.
Sometimes when you go on vacation you just want to be able to depend on the whole thing to 'click' without effort on your part. And FS usually succeeds.
In Maui and on the Big Island, they're the ones who set the standards.

I agree totally with Rick.

Another thing is that they don't nickle and dime you. We were there this summer. They have a wireless internet connection in their hotel. If you have a receiver in your computer you can surf the web wirelessly around the pool, for example. There was no extra charge.

We visited the Wailea Beach Hotel next door and learned that they charge $20 a day for cabanas around the pool. It was quite a contrast. The public areas of the Wailea seemed almost dirty compared with the Four Seasons.

Consumer Reports magazine occasionally conducts surveys of the experience of their readers with hotel visits. The only chains that consistently receives a rating of good value for the money is Four Seasons and Ritz Carlton.

You asked about discounts. The Gold AMEX card allows you to use their special travel agency. They sometimes have rates that are better than the hotel, often not.

Some agencies that specialize in very high end travel, can sometimes get you an guaranteed upgrade, especially if you are a good customer.

Just being a regular at one of their hotels help to get upgraded. We were upgraded from a garden view junior suite to a full ocean view junior suite the last time we were at the Maui facility. They don't have a frequent stay program, but they keep track of your comings and goings.

Thank you for the detailed responses regarding Four Seasons.
You have helped me to confirm my decision regardless that better deals have popped up at the surrounding hotels. My family is extremely excited about the trip. Thanks again. Mark