I would use: L'Homme by YSL.
If its sunny weather and an afternoon/evening affair, you'll want to wear something that can carry you through the evening. L'Homme is just the ticket IMHO. Fresh and radiant enough for the warm afternoon, but with enough substance and clout for a balmy early evening.
Keeping in mind you dont wanna be pointed and laughed at as the "cologne guy", this is a winner in my books.