Dress Code Guidelines 4 Upg on DL

Hey! I posted way back in April trying to decide whether to non-rev or confirm from JFK to PSA this July and have decided to gamble and do the old non-rev 'thang' - and just on the rare off chance there may be a business or first class seat available, can anyone tell me what the specific no-no's are for appropriate attire? (Men & women) Are men still required to wear a jacket and tie? Can women wear sandals? (It's been a waaay long time since I've non-reved!) Thanks in advance for any input!