One of the most respected pianists/singers/arrangers/musical directors working today, Dennis has worked with Jack Jones, Shirley MacLaine, Henry Mancini, Leslie Uggams, Neil Sedaka and Keely Smith -- to name a few.   His credits also include:  The Tonight Show, Late Night with Conan O'Brien and The Jimmy Kimmel Show.   Dennis received critical acclaim for his arrangements of Keely Smith's chart-topping CDs:  "Vegas '58 Today," "Keely Swings Basie Style," "Swing, Swing, Swing!" and the Grammy nominated "Keely Sings Sinatra."