Mixing people from different times seems too random, so I'll pick one time period where all these people could have been at the same party, the mid-50s:
Frank Sinatra
Johnny Mercer
Judy Garland
Keely Smith
Ella Fitzgerald
Anita O'Day
Louis Armstrong
Peggy Lee
Sarah Vaughan
Cole Porter
(not in order of preference-- I sit next to Sarah and put Frank at the other end of the table.)
On edit, I must add this bizarre factoid from the Johnny Mercer latest bio: That Old Black Magic is a very specific anthem to Judy Garland's cocksucking skill. Listen to the words with that in mind-- icy fingers up and down my spine...then the elevator starts its ride etc.