Becca, HID's are VERY hot - the exposed bulbs are a real burn hazard. By contrast, you're T5's are icy. However, you do get the most light for your utility dollar - once you get over the investment in equipment. Go to
http://www.hydrofarm.com to see some.
Because of their light intensity, you can also keep them farther from the plants.
I agree with John that it would only take a couple for that room, but you need to think about your overall scheme.
1) You will continue to use the enclosures for some plants - maybe you should consider which will be best enclosed, and which will be OK out in the room (you won't be able to keep the RH as high in the room as you can in the cases). Those plants will already have light.
Then there's the remaining ones - consider grouping them by light- and temperature needs, then think about what you might do for each.
I suspect that having a number of individual flat benches, each having its own lighting might be appropriate.
If the room is intended for plants, don't carpet it. You can always add it later, but you don't want to have to replace it due to the fertilizer dye stains and insecticide mists.