Personally i have only stayed at Caribbean Beach, but we did go 'touring' last time i was there.
I wouldn't like to stay in the Grand Floridian, it was too posh, and i felt really out of place.
If i could stay anywhere it would be Poly, cauae i love the theming and the monorail! Im not to sure on the contempory, it doesnt look that appealing to me!
I LOVED the Boardwalk, cause you can walk to Epcot or take a boat to MGM, which is really cool, plus theres lots to look at in the evenings. Also you can walk to fanastia miniture golf, which is fun!
I am 18 and to be honest i would just be happy to go to Disney! However do take into account size of rooms and bathroom space. Last time i went me and my sister almost killed each other, and we had seperate rooms and bathrooms! So maybe go for a cheaper hotel, but go for a larger room!
Hope this helps!
xxxx