Sorry for the late reply folks I've been busy busy with work!
As for whether the trays will be painted my answer is no.
I have always struggled with basing because of the numbers of miniatures I use in my games. I needed something cheap, standardised, and durable. I think if I paint or flock the outside of the tray they will not wear well. I would rather them be done in the same sand/static grass as the individual bases and the interior ground of the base is indeed finished in this manner. It's the damned edging! I figure the clear plastic edging is 'good enough' because once they're ranked up in larger battalions of multiple movement trays there is a weird beauty that apeals to my boardgame vs diroama compromise.
I would love to make giant battle dioramas like the kind you see in museums, however space is the adversary in this instance. When playing it becomes less about the miniatures and more about mechanics so I feel like the clear edge helps in decision making (i.e. how many units of Elves do my Gobbos have to kill before x happens... the situation become crystal with more defined bases, etc). I think once I retire I'll play a lot less and maybe I'll spend time making those aforementioned giant dioramas. I would have to make backgrounds for my tabe edges which would be a cool project in itself.
Final note on trays; I bought 10 plastic containers (for the lids) for a dollar at the dollar store. Seeing as I had so many to do that was a no brainer (and I'm still swimming in extras:). Over the years I have experimented (and rebased multiple times) using a big variety of possbilities. I've used masonite and drilled holes and placed magnets (makes set-up too long however and you can reuse trays if the number of minis are standard in a unit and sometimes they're not), I've used plastic strips and glued the miniatures directly to it (they pop off too easily). I tried the Warhammer way, but I absolutely hate using miniatures on square bases for skirmish games (great for ranking up, but crappy for war party level games), I've done scenic dioramaesque trays but then I made them themed (i.e. Drow had stalactites and such etc) but it accentuates the differences between between armies and company styles/scales and it was difficult to use troops from different armies (i.e. humans especially, and different Orcish/Goblin/Ogre/Troll/Gnoll troops can't be swapped in to create an army you want for the situation). I even made reinforced scenic bases out of Fimo and they weren't durable enough. So in the end I decided to do a standard accros the board.
I'm going to start a new thread and eventually catalogue all my fantasy stuff here and on my blog.
Thanks for the enthousiastic interest folks.