As much as many people want it to be "Dressin' Up," it would logically make sense that she is shooting for "Wide Awake."
--In interviews, she's said that the song was written with the movie in mind...
--The movie is coming out in July, so why not shoot a video to promote the song (a la Justin Bieber's "Never Say Never")...
--Lyrically, "Wide Awake" serves as Katy's realization that she can't continue to live in this Candyland world and that all good things must come to an end. It doesn't necessarily have to be about Russel or any of her failed relationships (as many have implied). Plus, Katy's next album is probably going to be a departure from the whole 'Teenage Dream' era, so it would make sense that she would use this song to transition to the next album.
I think a lot of people are worried about this being a "flop" because it isn't necessarily a summer song, and I agree. Be real though. Katy has already broken numerous records with this album. Im sure she doesn't really care about having a single that underperforms, because her main focus is probably to promote the movie.
Just my two cents.

could be wrong though.