IMHO, a shiny dash is dangerous, distracting, and annoying. I prefer a matte or satin finish. The important thing is protection. A good spray like 303 will protect well and not be too shiny.
Honestly though, I have found the best thing is what 69GTX suggested - Get a nice Dashmat. In my case, I hit the dash with some 303 every so often, just to make sure it's protected and treated, and keep the Dashmat on it all the time to keep the sun (and glare) off.