Good reading from Bernhard Roetzel on the summer suit:

Many gentlemen will hesitate to don a linen suit unless they stay in Capri or Sorrento. It is rather a matter of colour than of material whether a linen suit will look out of place on the summerly streets of New York, London, Brussels oder Zurich. A blue linen suit would be suitable in all of these towns, just like a garment in darker colours like tan or tobacco. Only the white linen suit might look a bit out of place, especially for office wear. In New York one will find another classic summer suit that is almost invisible elsewhere. The American answer to the Italian linen suit is the the single-breasted seersucker suit. It is named after the cloth that it is made of. To create the typical wrinkled effect the base threads are stretched while the weft threads are looser.

There is a lack of selection in lighter summer fabrics for American RTW suits, and I wish we had something else besides seersucker. Luckily, European companies are much more adventurous – some selections from Kiton: