I'm a very low bass though can stretch to baritone as wel--it has been particularly a problem for me because I'm a very strong dancer and often at local auditions one of the few guys who has a big dance background--and dance heavy roles particularly are rarely done for lower male voices...
Let me try to think of some of the audition songs I did
Look at some of the cross over Broadway CDs recorded by operatic basses like Sam Ramey or darker baritones like Bryn Terfel or (even lighter) Thomas Hampson.
When you say baritone, how high do you mean? Is F# doable? If it is, then something like "If I Can't Love Her" from B&B or "There but for You go I" from Brigadoon could be good choices. Also some of the Kiss me Kate Music is set pretty low.
Other than that, did you enjoy the play Mrs Lincoln?
Basses rarely 'belt' per se. They might sing manfully or some such. However you can sing just about any song although you might need it transposed down. Don't worry whether the song was written for a bass. Rather think of what you can bring to the song.
Frank Butler in Annie Get Your Gun is certainly a dark baritone. Take a look at "My Defenses are Down".
There is always South Pacific, The Most Happy Fella and Milk and Honey.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.
WHat about "This Nearly was Mine" from South Pacific? I don't know how high it goes. At first I was going to say Make themr Hear You from Ragtime, but that really gets up there at the end. I Won't Send Roses from Mack & Mabel?