Depends on how high you want to go and your own personal tastes. However, all of these are pretty good (in my opinion)...
Streets of Dublin - A Man of No Importance
Love Changes Everything - Aspects of Love
What Is It About Her? - The Wild Party (Lippa)
Valjean's Soliloquy (What Have I Done?) - Les Miserables
And if you have the range and feel like going super high, there's always things like Gethsemane from Superstar or Pity The Child from Chess.
You may also want to check out The Singer's Musical Theatre Anthology songbooks for Tenor. There's 4 volumes and they also sell practice CDs for each volume.
Hope that helps.
Every passing minute is another chance to turn it all around...