Good choices for building a strong vocal repertoire (mezzo)?

Question:

Good choices for building a strong vocal repertoire (mezzo)?

I'm considering beginning to audition for local choirs/other music groups and/or some musical theatre. I have a very small selection of songs that I know to choose from - mostly folk and classical (a very vague smattering of musical theatre.) I'd like suggestions of songs to learn to cover a variety of styles.
Note: I'm very comfortable with Spanish or Italian, but I have no knowledge of German or French so, while I know there are some wonderful pieces out there, please nix suggestions in those 2 languages for now.

Best Answer - Chosen by Asker: I am a 2nd year, mezzo vocal performance major. Here are some pieces I have sung in the last couple of years that I would recommend. They vary widely in range, as I was a soprano until about a year and a half ago, and they also vary in availability, as some are pieces my voice teacher just happened to have and that you may have trouble finding. Nonetheless, look into:

Classical:
The Black Swan (Menotti)
Cangia, cangia tue voglie (Fasolo)
Che far senza Euridiche (Gluck -- very popular mezzo aria, also very dramatic. Includes recitative.)
Domine Deus (from Vivaldi's Gloria)
Luke Havergal (John Duke -- this is an amazing modern English aria)
Non e ver! (Tito Mattei)
Pie Jesu (from the Faure Requiem)
Music, when soft voices die (Ernest Gold -- great setting of this text)
Stopping by Woods on a Snowy Evening (Paul Sargent -- a hard arrangement to find, but absolutely fabulous)
Come l'allodoletta (Donaudy -- minor, slow, beautiful)
Old Song (Douglas Moore -- English art song)
Quella Barbara Catena (Ciampi -- sorta high, sang this when I was a "soprano")
Sebben, crudele (Caldara)
O del mio dolce ardor (Gluck -- also a bit high for a mezzo)

Musical Theater:
As Long as He Needs Me (Oliver -- ballad)
Another Hundred People (Company -- belter piece, not great for me but if you're a belter, this is a fabulous song)
Not a Day Goes By (Merrily We Roll Along -- ballad, love this song)
Pirate Jenny (Threepenny Opera -- a dark piece, but if you can get into the character right, can be very powerful)
I Wish I Were In Love Again (Babes in Arms -- can be done with a baritone as a duet)

Jazz:
The Man I Love (Gershwin)
Love Me or Leave Me (Kahn/Donaldson -- very low, down to G below middle C, pretty upbeat)

Folk:
Rainy Night House (Joni Mitchell -- her stuff is LOW, basically alto with some higher parts)
For Free (Joni Mitchell again, and again, LOW but gorgeous)

Hope that helps, I love these pieces.