I print on 13 x 19 inch paper all the time.  In Vue I set my largest number at either 2200 pixels or 2400 pixels. I start at 2400 pixels and if the render time seems too long, I drop it to 2200 pixels. Tjat drop can make a difference. The other number will follow depending on what picture ratio you have set in the camera settings. I, then, use onOne Software'sGenuine Fractals or Alien Skin's Blow Up  to blow it up. GP suggests that for Epson printers you use 240 or 360 dpi and for HP you use 300. I forgot what it is for Canon. I think 300.

I have reviews of both products on my website of perpetualvisions.com

As Silverblade said, the dpi in Vue is  72.