The last two major shows at the Getty, a huge museum here in LA, featured Irving Penn's Small Trades series, pretty much nothing larger than 16 x 20...and now the Frederick Evans platinum exhibit (amazing show you must see!) also with prints mostly smaller than 16 x 20. Their "Workers" exhibit just closed, almost all under 16 x 20 (there was an incredible Salgado print there!)...also the SB Museum of Art hosted the Brett Weston show last summer, same as above.
Oh, and last year's Michael Kenna show at a private gallery in Santa Monica showed his mostly 8 x 8 -ish prints.
I understand that Nick Brandt's show last year at Fahey-Klein featured very large prints of his incredible African series.
Just some food-info for thought...