I often get a windowpane suit confused with just plaid suits. Many people use these terms interchangeably and there isn’t a real ironclad definition for it. Most men’s style gurus that it generally means suits that have “panes” that are about 1.5 by 1.5 inch square, although they can be larger. Other plaid styles tend to be a little bit smaller and more subtle.
Windowpane suits are more suited to guys who want to be a little more expressive with their fashion. Because of the large patterns, they’re generally not recommended for larger, more rotund guys. It can be a good look for a taller, slimmer man, where stripes might make them look even taller.
A very loud pattern can make it look like you’re trying to relive the 80s, so the right pattern and color combination is key. Plaid, and the windowpane look in particular, has been put back into the spotlight in the last couple of years due to the success of Mad Men.
While Mad Men shows the look in an office, in reality it’s a tough look to pull off there. Investment banks or other conservative industries generally go for the navies and greys. It's is probably best suited to a more dress-down look, or a creative or visual media type firm where creativity is encouraged.
Most people encourage the two out of three pattern rule, and with these its especially important. A windowpane design, checkered shirt, and a striped tie can just be a lot of pattern processing for people and make give you a headache! A solid basic white shirt and large pattern tie often works well.
Its becoming a popular style across all manufacturers these days, even Italian makers. Zegna has some beautiful designs. It seems to be more widespread in the States, with Brooks Brothers and Calvin Klein among dozens with these available.