Doing a great poster on the cheap
Printing up a 3' by 5' poster at Kinkos will set you back about $200, and it will be on flimsy poster paper and require a special tube for mailing or checking through. As an alternative, you can design a 2.5' by 5' poster in three 20 inch by 30 inch parts and have these three parts printed as though they were photographs at the online Costco photo service. Costco Photo Center You can, of course, pick alternative services.
What I do is design the piece like a triptych so that the images and text are not split between the three parts. The most important graphics are on the center part. I do the design as three Adobe InDesign files (you can choose any poster design software) and then export them as high resolution (300dpi) tiff images that I then export into high quality JPEG files.
I upload the three files to my Costco photo account and then ask Costco to print out glossy large-scale prints, 20" by 30" each. Costco charges $10 per print (so, $30 total) plus some shipping. If you are in a rush, you can have them ship directly to the Hotel! It takes about 2 days to get the print done, and 3-5 days for the UPS service. The total cost is about $40, and it comes in a tube that you can carry on the plane and shove into the overhead compartment. The paper is thick and the images and print are super clean.