I was going to suggest the "sand and melamine paint" idea, but then I couldn't remember if the Trillium
table top was "real" laminate or more of a paper or thin vinyl laminate (think: fancy Contact paper). Doug probably knows though
As for "varnishing" over a map, as much as I like real, old-fashioned varnish, I would probably use something like a polyurethane (varnish-like product but a different formulation). I'm wracking my brain because I just read where a fellow did this on a flip-up table by using an old chart (map) and I think he used a special "bar top" type clear finish that ends up looking like 1/4" of hard clear topping (if you like that look). I feel like it might have been a self-leveling epoxy or something. Will post back if I find it again.
Edited to add #1: Found it! I had it saved. Here is some info:
1) He took the table apart (it had teak edging strips and a Formica laminate main surface).
2) He sanded the laminate part to roughen it.
3) He wanted a thick, clear epoxy coating on the table (1/8"), so he used about a 1/2 liter of clear epoxy (my note: epoxy does not stand up to UV rays, so that is something to look into; not sure if the "bar top" stuff has added UV resistance).
4) He tested the chart print for color-fastness and it was not affected by the epoxy (it was an antique chart). He put the table in the oven to warm it up and accelerate curing but found it was unnecessary and almost made it cure too fast.
Here are photos:
Edited to add #2: This is the stuff I was thinking of. The site is a bit "home made" looking, but I have heard good things from people who have ordered other products from him.
And a thread discussing some other options:
I have seen someone post to this forum (a while back) who did the photos under plexiglass thing - it was pretty neat. You can sand the edges of plexi and they end up smooth and opaque; kind of like "sea glass."
Fun thread with interesting ideas