I would easily choose CSR and here is why....
You are getting the
free dining and paying rack rate for the room. The price of the hotel in turn decided the % you are getting off with the free dining. There is more bang for your buck going with a moderate then a deluxe. Why pay $1000 more for the same exact free dining plan. If you do decide to do a deluxe, wait until there is a % off rate or specific dollar amount off - it will seem more worthwhile.
I have stayed at the Poly and I do love the grounds and atmosphere but the rooms are showing some age and even though they are slightly bigger, it doesn't justify $1000. A lot of 2nd floor rooms have no balcony either so the amentities in the room are the exact same as CSR if you get stuck in one. For me if I pay that price, I better get a balcony!!! Poly's bathroom is slightly bigger and has a daybed, thats it - no difference.
Yes, the monorail is great and yes seeing the castle on the lagoon is nice but I thought the bus service to AK and MGM was the worst I have ever seen so the "monorail resort" wasn't great overall for transporation. The AK bus was shared with the Contemporary and was almost full when it arrived. Then we had to drop people off at Blizzard Beach then finally go to AK. In total waited 65min from arrival to bus stop to AK.
CSR does not share a bus with any other resort and has a much bigger theme pool along with 3 other pools and LOTS of lounge chairs. As much as I loved the Poly Volcano pool and the zero degree entry it was MOBBED with kids and adults ALL THE TIME and that was in May. So much that you couldn't swim just sorta tread water in place,

They also had NO lounges throughout the whole day and ran out of kids life vests. Another problem with the Poly pool is it surrounded by the volcano, trees etc... which is beautiful but lacks the parents to sit down to actually see their kids. There are only a few lounges and chairs that you can see the whole pool from - which in turn lead so many parents standing around in the zero degree entry side the whole time - not relaxing. I like to be able to relax in a lounger or chair and watch dd and dh play in the pool. At CSR it is very open and accessible to seeing the kids, even on their water slide. I think CSR has a good balance of kids and adults and that is what I am looking for.
I don't want people to think I am bashing the Poly though, I do love it there but late August, I can only imagine mobs and mobs of kids at that pool on top of the pool hoppers and other resort guests that come into to see the fireworks etc... Just a little too hectic for me. No matter where you chose though, I do highly recommend Ohana's - yummy!
I love Disney thru and thru and go hard all day but when we head back to the resort I want some R&R to get me ready for the next day.
Save yor $1000 and either rent a car (which is great for the free dining - you can resort hop easier) or just pocket it for your next WDW trip.