IF you REALLY want something, it's better to book what you want, assuming you can afford it -i.e. that you are comfortable paying that rate, without going into debt say. You can check for discounts, and if they become available, they can be applied to your room.
You should not book a lesser room and count on an unpsell. I've never been offered one, and I've been many times, but then I often go with a discounted rate. Though I was offered an upgraded room location during a non-busy time once.
On the other hand, I'd never pay rack rates for the Poly. Maybe once on a splurge trip, but generally, I know I'll have a great time staying somewhere else for less- a lot less.
At the very least, I'd stay at the Swan again. Different perks (near MGM and Epcot instead of MK) but when discounts are around it's nearly half the cost, with all the same level of quality. It's a great resort in a great area! It's really hard to justify spending any more. We've also had great stays at the mods.
So if your asking whether you can have a great trip staying somewhere else for less, my answer is yes. If you really want Poly and can afford it and will be disappointed by not staying there wiht that view, then stay with it.
