Thanks for the response Ariana,
I thought the ZAZZLE team would toss in a comment as well....

... but perhaps I need to e-mail them direct on this.
Regarding your comments: Yes, I know the blue-ish tint you're refering to with Zazzle's cheaper 'glossy' poster paper(I've had several made). Despite this little anomoly, the contrast is bold... providing good depth to the image. This paper is not archival, however, so I will likely try another large print on the "Silver" category paper (glossier than Bronze).
Epson makes a wonderful Heavyweight matte paper that is terrific for desktop printing, so I thought I would get similar results with Zazzle's bronze paper. Not the case.... flat & monotone as I stated in my initial post.
I'm quite confident that my frustration is merely the paper I chose, and will likely get different results with different paper. (Not sure of Zazzle's ink application, but it appears to be an ink-jet system of some sort, (not particle adhesion as in toner). A liquid, sprayed to a surface, is bound to soak INTO the paper, thus the situation. A glossy (hot pressed paper surface) should resist the soaking, so the ink sits ON TOP of the paper with more vividness/saturation, etc.
blah blah blah.... LOL (too much tech talk) .......... Thanks again.
P