Hi Mike,
I haven't taken many astro pics that I've printed, but normally I get enlargments bigger that 8"x12" printed on Kodak Professional Endura metallic paper. I like this paper because it looks good in almost any light, and has rich vibrant colours. It's glossy paper, but I find it much easier and nicer to look at than standard gloss paper. Fuji also have similar paper, but I'm yet to find anyone that uses it in Australia.
http://wwwau.kodak.com/global/en/pro....24.24.5&lc=en