I grew up, as did many of us, in the film era where 11x14 was big and 16x20 was really BIG! Now, I now print digitally where the "only" thing required for a really large print is a large format printer, a piece of paper, and the will to spend a lot of money on paper and ink. Big is relative. My work prints are 6x9, my standard exhibition (and rare sale) size is 9x13 and REALLY big is 13x20. Who has all that wall space anyway?
Some images don't print well large. My most popular image is a sea stack from Bandon, Oregon. The stack itself is black, really black. When printed larger than 9x13, there's a big black blob in the middle of the photo. My solution? I don't print this image larger than 9x13. I confess though that while many images are quite lovely at 6x9, or even 5x7 (so long as it's not for reasons of poor technique) occasionally a large print is really sweet.
I'll be attending the Photolucida portfolio walk later this week in downtown Portland. It is absolutely fascinating to see what is new and "cool" in contemporary photography. Each time I attend, I learn. Some folks use the "if you can't make it good, make it big approach;" Others show jewel-like images at 4x5. If they've used good judgment, and even some of the large scale printers often do, it's spectacular.
In any case, I agree with Wayne Fox, though at a somewhat smaller scale. One must be critical of the image, often a large print is rejected not be a technical flaw that grew almost out of proportion, but because it just doesn't look right. I enjoy what I do these days; I hope everyone else does as well.