Flyleaf and Paramore. Awesome choices.
Anyways, I listen to a lot of Switchfoot's new stuff, which has some pretty uplifting songs (especially off of Hello Hurricane) with a dash of some depressing stuff, but a healthy dose for some reality.
Maybe try Nightwish out? Think Evanescence but with a bit more orchestral involvement. Best album to date they have in my opinion is Dark Passion Play. First track, The Poet and the Pendulum, is a masterpiece. Once again, some uplifting stuff, some depressive, but both in healthy doses for reality.
Hm... as for exclusively uplifting songs, I'd have to go for Family Force 5
My friends got me hooked, and they're the only ones that come to mind. For a bit more, er, mature-ish band, I'd go for some Trust Company or possibly Rise Against if you like their styles.