For me there are two types of formal - business formal and pleasure formal.
Business formal is cerebral, cold, subtle, clean, serious. I think fresh, woody, green, soapy, metallic, mineralic notes. Bvlgari PH, Platinum Egoiste, Grey Vetiver, for example.
Pleasure formal is mysterious, rich, smart, complex, seductive. I think woody, spicy, oriental, mossy, smokey notes. Sycomore, Chanel PH, PdN New York, for example.