I would say Green Irish Tweed. However, I would also recommend you look into sampling D'orsay - Le Dandy. You might also want to sample these fragrances considering when I first came to this board I almost bought some creed fragrances blind. I learned quickly after sampling several that I was not fond of ambergris which is very common in Creed fragrances.
Personally, I would wear Green Irish Tweed with the khakis shirt and tie. I would however wear something else for when I wear a suit. If you are a fan of ambergris I would recommend you consider Bois du Portugal. Seeing on how you are 28, you shouldn't feel it is too mature for you. Me personally, Le Dandy is what I'd wear with the suit.