A few ideas that might help in building your dispay cases. This picture shows the ten 2' fixtures and nine 4' footers installed vertically. That's not the most cost effective, but with my case width it was the only option. 2' fixtures cost more than 4' ones.
When planning you have many choices, like size of case, type of wood, shelves(glass, acrylic or wood),sliding glass doors or not. Study the display cases pictured on ICON that Mark Corriero, Brian Riecker and others have posted or better yet have them build it. I went with a cabinet maker that was building my kitchen cabinets. Make a good set of plans and good luck :)
The total width of the three cases are 8' and 7'6" tall (center one) with 7' side cases. The reason I picked three cases about 32" wide is two fold. I have three sub collections LRI's, 160's and purple. Also with the varied depth and heights between the side and center cases you get more of a pleasing look, verses a wall of wood. The center case is pulled 3 1/2" off the wall and attached to the side units.
The depth of the cases are critical. If you make the side walls 12" deep and use 5 1/2" shelves, the lightning distance from the diffuser will be almost perfect. Too close you will see hot spots and too far back dark spots. The sign white acrylic is another headache. You have to choose the grade and thickness. I went with 1/8" 2447 grade. Wanted to use 3448 grade but the supplier in my area only had 2447. The lower the number the less transparent the diffuser is. So with the "darker" grade the bulbs must be closer to the white acrylic.
The bulbs are very important to our hobby. Use 5000K, 86CRI to get daylight color. The CRI (color rendering index) is as important as the bulb temp.(5000K). The higher the CRI the closer to sunlight, as well as more money to spend. Check out bulbs.com for prices.
More building suggestions to follow latter.