I run an RPG Map Printing service called Gamer Printshop (hence my name), and print large format maps up to 36" x ?, though I can use 42" paper photo satin media, then offer lamination. Some guild members use my service - see my Sig.

Of course, I print many of my maps all in large format sizes, laminated then used in our Pathfinder games, so I'm kind of lucky that way...

GP