Three 26" Euro shams will go across the head of a 76" wide king mattress perfectly. Generally, it is recommended that you buy an insert 2" larger than the size of your sham. I prefer down or feather (cheaper than down) inserts to polyester fiberfill because I like a softer, slouchier look. The fiberfill inserts will give you a stiffer, fuller look. It's really a matter of your preference.

Thanks Mitch! I prefer that size for my sofa in case I ever need to take a catnap. :) Blubird, I sure wish I knew to buy a couple of inches smaller in the cover before I bought a pair. Seriously, does anyone know of an online store that sells a lot of textiles, like pillow covers with many colors and patterns to choose from? I'm looking for checks and plaids and they're really hard to find, or not the color I want.

I have the Vanessa duvet (queen size) which I have paired with an ivory matalesse coverlet. I also debated what to do for the shams and whether to get the euros or standard sized ones. I first bought the euros and paired that with matalesse standard shams. I don't have a pic of it together with the duvet, but hopefully you can get the idea: As I preferred using the duvet at the base, I wasn't too enamoured with this look, felt too much of the pattern was hidden by ivory shams so eliminated the matalesse shams and exchanged the euros for the standard sized ones like so: I liked this much better, but still felt something was missing so ended up finding some ivory ruffled euroshams and a decorative center pillow which I felt completed the look: Not sure if you can tell, but in the last pic there is no duvet insert, the second one there is. I plan to use the insert seasonally. HTH!

I don't think there's a specific trend except that manufacturers would rather make standard shams because they take less fabric. Pottery Barn, for example, seldom offers matching Euro shams and many bed-in-a-bag choices exclude Euro shams. I have both types. In one bedroom, the Euros match the duvet cover with contrasting accent pillows and in another bedroom, it's the opposite. I rarely have both Euros and standard shams that match the duvet cover, but that's because I like a more eclectic look.