I find turtlenecks to be universally awful. Thankfully he agrees. Otherwise, thanks for the tips, guys! He mostly has black and dark grey stuff right now but I really want him to branch out in terms of color, and this will help a lot.
I guess I feel like men's wear is pretty boring because it's almost always the same shape. He can really only wear one type of pant (flat front, slim fit, straight leg), one type of shirt (though I guess the collars can be slightly different?) and similar shoes (he doesn't like the extended toe-box look so round or squared toes are about it). The only things you can change drastically are colors, though that can be pretty fun. Women can drastically change their silhouette every day if they feel like it, and can wear so many different types of shoes, even just within business-wear.