You probably already have a very good idea of standards people are likely to request.   It's hard to know what to suggest to you without knowing more details of the actual job. One other factor would be the ages of your likely listeners. I would think--not knowing more details of the job--not even the country you are playing in-- that unless the age of listeners is below 30, Gershwin, Cole Porter, Irving Berlin are likely to be requested.   As you no doubt know, things like "Summertime", "I Got Rhythm" "Someone to Watch Over Me".   Songs from musicals maybe--"Old Man River", "Can't Help Lovin' Dat Man" etc.   Classics from movies:   "As Time Goes By", "Moon River", etc.

This is very much a stab-in-the-dark situation:   we really need more details about the job. Who knows--maybe a lot of Beatles songs and other rock requests. Depends on the clientele and what management is looking for.