I liked Carolynne, and am always thinking of her when I see \Carly! (Especially when she sang I Drove All Night, like Carolynne did) - Carly's real name's Carol too!
On the subject of Carly, as I've said before maybe she should try Hurt by Christina Aguilera - definitely CA's best song, and works well with a voice which isn't entirely in control, if you know what I mean, but would showcase several facets of Carly's voice, plus it's modern!

I'd also like to hear her try "Mercy" by Duffy (before it starts being wheeled oput on every UK talent show!) but that's not likely to happen
I'd love to hear my favourite, David Cook, try "A Little Respect" - rocking it up of course, like Whea\tus did, a few years ago - but even more so He could dedicate it to Slymon - it's about time he paid David a little flipping respect! Lol

Iris by the Goo Goo Dolls would also be a good song for him, or one of Nickelback's - maybe How You Remind Me rather than my original suggestion of Rockstar, he might be too down to earth for some of those lyrics, lol!
I love Kristy too, she really needs the right song now and I'm not exactly sure what that is. "It Must Have Been Love" by Roxette might work well, and it hasn't been used as often in the US as it has over here (Carolynne Good sang that too! LOL) but I don't know whether it'd have the impact that I'd like Kristy to have so I'll keep thinking!
Brooke needs to sing something upbeat - possibly "Walking On Sunshine" as she doesn't seem capable of leaving her happy, sunny little world - good song though
I don't much like hearing Ramiele sing anything, I'm afraid - but maybe she could try something by Nelly Furtado like "Turn Off The Light", the other name which usually springs to mind is escaping me now though!
Still working on the others - for some reason I always find David A and Chikezie especially hard to choose songs for - and they're my favourites after David C and Kristy!