Teaming a beige trenchcoat with a navy blazer is an awesome option for a classic and polished ensemble. If you wish to easily play down this look with a pair of shoes, introduce navy and white canvas low top sneakers to the mix. When leaves are falling down and autumn is in full swing, you'll appreciate how great this getup is for transitional weather. And if we're talking casual outfit ideas for 30-something Millennial gentlemen, this outfit is perfect.