#1. If you never want to think about what to wear to the office again, invest in a single-button flannel suit like this one. When expertly tailored (note the hem length on the pants and that the cuff of the shirt is showing), it's a workhorse in your wardrobe.

Suit ($1,195) by Calvin Klein Collection. Shirt ($325) by Ralph Lauren Black Label. Tie ($150) by Alexander Olch. Pocket square ($130) by Dunhill. Shoes ($570) by Church's. Socks ($7) by Gold Toe.