I'm so very excited and happy that you will be going to WWD and staying at the Poly.
I have never been to Disneyland and I'm sure it's amazing. And having said that, I know I have no authority to compare the 2. But, I do know that Disneyland is landlocked and unable to expand. So, in my mind, the fact that DDW is over 45 square miles with 4 major parks, 2 water parks, numerous golf courses, Downtown Disney, etc etc. it makes it that many times more awesome than Disneyland.

Staying at Poly is like the icing on the cake. Although, to me, Poly is the ultimate place to stay at WDW. I'd like to make one suggestion.
Please allow me to tell you a quick story before telling you what that is.
I had been to WDW a number of times years ago but had not stayed at the Poly. The the time came when I got to take my whole family including my princess grand daughter of 4 for her first time. Nothing but the best for my little princess
While making my reservations, I was asked if I might want conceirge level. I didn't have the benefit of these boards and photos at the time. In fact, I didn't even have a computer at the time.

So, I asked what concierge included and i was told that there would be juices and cold cereal for breakfast, cookies and snacks for lunch, hot hors dourves (spelling?) for dinner and refreshments at night....oh yes, and a chocolate on your pillow at night. I don't remember the exact cost at the time. But, I do remember that it was additional $$ per person. I decided that my group of 9 could do something really special with that extra money and that snacks weren't really that big a deal for us. So, I booked without concierge level. When I mentioned it to my family. They were disappointed, pointing out that it was the first time all 9 of us would be together, that we would be there for over a week and having a lounge to gather at and relax and snack would be nice. Then my princess

said "please grandpa". Well needless to say that a 2 minutes phone call later, we were booked for concierge level.
I have never experienced anything so understated in my life. The food was incredible with sooo much variety. It was available all day. The evening "refreshments" were top shelf drinks. The lounge is beautiful. The Cms are incredible. The level of service impeccable. It was the best extra dollars I've ever spent. So, what I'm saying is, if you can afford it, definitely go with the concierge level. And my only warning would be not to eat too much of all the goodies they put out. You can easily save the cost of at least 1 full meal per day without ever intending to.
Sorry if I got a little long winded. But i just can't say enough about the Poly and my experiences there.
May you have a wonderful vacation and I hope your memories will be as awesome as mine.