I've been using the Epson premium glossy paper. I got a good deal on it earlier this year not long after getting the printer (Epson 8550), and laid in a supply. The printer was expensive, but the tanks make for far cheaper printing than cartridges. Supposedly, the premium paper prints last longer than the standard. This is attributed to how the ink penetrates the paper. I can't really tell a lot of difference in the look of standard and premium paper prints.
I've tried the matte and like it for certain images. Matte obviously has a softer look, and the glossy provides better resolution. The Matte can be had a lot cheaper.
The Pup and I are printing a cross section of our images. She is making a portfolio. I'm just printing a couple of my "better" images for display. We are finding that if we are planning on displaying single prints, we prefer to go bigger than the standard 8 1/2 x 11. We also aren't happy with the truncated aspect ratio of 8 1/2 x 11 for most pictures. For the stuff going on the wall, we print 11 x 17 and get the software to stretch it that extra 1/2" width, or trim to 11 x 16.5.