Multi - Deck Layouts

I am designing a new layout, and am having difficulty coming up with a good way to support the upper level. I have thought about angle brackets, and straight 2x2 supports, but I do not want to obstruct the view of the lower level. MR feature multi deck layout all the time, but never discuss how the upper levels are supported. Does anybody have any suggestions?

MULTI DECK LAYOUTS ARE GAINING IN POPULARITY BECAUSE YOU CAN PUT TWICE AS MUCH LAYOUT IN THE SAME SPACE. THERE ARE MANY BOOKS ON BENCHWORK THAT WILL SHOW YOU HOW TO BUILD SUCH A LAYOUT. SOME ARE OPEN GRID AND SOME ARE L GIRDER CONSTRUCTION, SOME ARE A LITTLE OF BOTH. GOOD LUCK