It might seem that those places are far and unreachable, but actually it is easier than it sounds. Every dream can come true!
Every location has its pluses and minuses. The most important thing is to be there early. The earlier in the summer you get there the easier it is to look for your job and housing. You should do a lot of preparations and research before you go, because it is much easier this way on the spot.
You should mostly pick a place where the tourism season is booming during the summer. If there will be more customers the employers need more staff. Also, you have much more fun if you pick a location where there is something interesting to see and do.
The choice of the destination depends mainly on your personal preferences. If you are a party animal, you probably like Florida, if you like big city life you might want to pick New York. Nature lovers land surfers like Hawaii the most.
The choice is yours!