Bill D:
That black plastic mesh is exactly what I have on my flight and I've had no problems with it. I originally wanted the metal mesh and would just paint it black but that would cost more time & money. I don't think you'll run into any problems w/ it if you'll be keeping your cage indoors. If you can, just use the mesh for the top of the aviary, there will be more than enough ventilation and ALL the mess will be kept inside.
You can get a mural from ebay, it's a lot cheaper than buying one from stores and there's a lot of good choices. You might want to consider wallpaper which is pretty cheap. I originally intended to put cloud design wallpaper (the birds will be really easy to see with the light blue and white design) til I saw the garden design I'm using. For the size aviary you're building, there are lots of nice big ones from ebay! Here's one (although a bit dark)
http://cgi.ebay.com/AUTUMN-FOREST-Path- ... 7C294%3A50
Here are some ideas you might wanna consider that'll make your life easier

:
Use aspen or pine shavings for flooring so you wouldn't have to clean that often, I just rake it every now & then and replace the shavings every 3 to 4 weeks. What kind of floor are you considering? How will you be cleaning it?
For a bird feeder - Don't use the bird feeder I have in the pics. Although it's super cheap, the birds like to sit on top of it and poop all over it! I now use a wild bird feeder I got from Home Depot (also cheap, about $4-5). It's green and is a tall cylinder type. It has 8 holes where the birds can feed from and the birds cannot poop on it. The good thing about these wild bird feeders is that the seed hulls drop off after they eat the seed unlike if the food is kept in dishes which you have to clean everyday and blow the hulls from. Plus , you don't need to disturb your birds that much. The seed in the feeder lasted me more than 2 weeks for 9 birdies.
Here's a design idea for perches - I wanted the perches to be situated so that viewing birds would be easy. If I stick them directly on the backboard, some birds would be harder to see if others are blocking him/her from view. I bought a wooden dowel (Lowe's) and cut it to 1" pieces & drilled 3 holes in each one. The middle hole is where I screwed the perch on and the 2 holes on each end was screwed to the side of the aviary at an angle. I hope you can view it here:(try zooming it).
http://brenice.multiply.com/photos/hi-r ... Daddy%2350
I did place 1 perch through the backboard (& mural!

) so it would appear that it was coming out from the picture.