I learned the hard way that linen trousers, if they're satin lined, are definitely not comfortable on hot days. Doh.

One thing there's still a dearth of in the marketplace is men's trousers with stretch. I had a pair of gray stretch cotton/spandex (~5%) slacks from Banana Republic 8-10yrs ago that were absolutely perfect for anything, but haven't found much else similar since.

Imho, a simple wardrobe is great but being able to execute on the plan depends wholly on one's lifestyle.