You will have a AWESOME vacation!
Just make sure you go with the thought in mind that having a "perfect" vacation doesn't always have to mean "85 degrees, sunny, no lines, no cancelled shows, fast buses, perfectly cooked meals..."
If you have the basics covered......reservation in hand, traveler's checks...or lke we do, pay ahead and that way you only need the room key!

and essentials like sun block, bathing suit, comfortable shoes.

Then you will be fine.
Some of the most memerable moments happened when we were faced with what we thought were "problems"......like when a huge storm blew in so fast while we were trying to head over to TOT at MGM. So instead of running through the rain, we headed in to the Who Wants to be a Millionaire for the 3rd time......Well, the 3rd time was a charm bacause I ended up in the "hot seat" and got up to 32,000 pts!!!! One of the most exciting and fun things we did that trip and all because it started to storm!!!!
Or when they had to cancel the Tapestry Parade at Epcot because of the wind! Ended up spending more time going throught the different countries and really spent time with the people! My DD met some of the most interesting people and ended up writing a report about it for school and got an "A" on it and it helped boost her grade for the semester. Cool, huh!
So you see......WDW is MAGICAL in so many ways.....that you have to sometimes remember that when one door closes.....look for the open window....or better yet.....look for the door that leads to the Castle!!
Have a great time!!! I wish I was going now too....but have to wait til next May.
ps....you will LOVE the Poly...it is our favorite. Don't fret about the rooms, etc either....all the buildings are great. The first time we went, we didn't get our request to be near the Cerimonial House, ended up farther away, BUT in a perfect location to see the fireworks from our room! It was an awesome room!

And very near the TTC so we could hop on the monorail to Epcot in a matter of a few minutes!