I know that many people are happy with monitors stacked vertically, but I have had trouble using this type of layout in the past: a sore neck and minor, but persistent headaches from tilting my head up to see the top monitors. The recomendations I found for an ergonomic setup were pretty consistent: keep the top of the viewing screen at eye level, so that you are looking forward and down, rather than up. A vertical set up probably won't bother many, especially if they are only glancing up occasionally, but something you might want to keep in mind.
Just a small suggestion: three 24-inch stacked on top of one another is gonna cause a major pain in the neck after a while. I run a 5 monitor setup as well, one 24-inch, and 4 20-inch. The 24 sits solo in the center, flanked by two stacked 20-inch on each side. I find that I don't really focus on more than 3 screens at a time, which is what the 24 and both bottom 20-inch are for. The top screens, I mainly use for charts and what not that I glance at once in awhile. The advantage of this setup is that you have 3 monitors at eye-line, which really makes a huge difference in comfort if you're planning to spend 8+ hours a day looking at screens.
If we keep the current desk we will be using poles without bases and we already own 99% of the ergotron hardware/brackets, etc. If we don't keep the current desk we will get a new desk that has brackets already built into them.
Agree strongly!!! Very very strongly. I ran three 22" landscape stacked vertical. Tried the stack at different heights. At all heights I found it was just too much of a vertical travel for the neck, and "peripheral" vision for noticing changes beyond a two monitor range was all but non-existent. I had the pole setup to stack four but never put the fourth on as three was too many. Ran this for near two years; I was surprised to be very relieved and relaxed to lose the three high setup. Less physical stress and its resulting mental stress and distraction. Went to three wide, two high, and with 28" monitors in landscape. Two high is much easier to work with. Left and right monitors are angled inwards. Distance from outer viewable edges is 68". Viewing Distance, bottom row: eyes are 35" from the center monitor, 41" from the outer viewable edge of the side monitors. The bevels of the bottom & top monitors are touching and adds up to 2.5", which I don't notice in use. The distance from the viewable bottom of the lower monitor to the viewable top of the upper monitor is 32". Height: My eyes are level within an inch of the top of the screens on the bottom row. Very easy to view: - entire center monitor on bottom row, - first half of side monitors on bottom row, - bottom third of top row monitors for: center monitor and first half of the side monitors. Slight head movement required to view outer halves of bottom monitors, but that gives full and easy view of that entire monitor and the bottom 1/3 of the one above. Noticeable head movement required to view the middle third of the top row monitors, and more head movement required to view the top 1/3. While viewing any monitor, all of the other monitors remain within peripheral vision. Any flashing boxes noticed and many other changes/movements. When eyes are focused on the bottom row, less noticeable is the top 1/3 of the top row. One must scan and not rely upon movement/change to be noticed. Strangely, when focused on the top row, the entire bottom row remains "within notice". I find this very easy to use, easy to sit in front of and easy to scan. Was running four of these (2x2 landscape) for better part of a year. Just went to the 3 over 3. Although I not the technical differences in viewing a three wide setup, I find it just as relaxing to use as two wide, and more so now that I can scan all that I want to scan without having to click on something to bring it up and have it hide other data while it is viewed. If going for four 28" monitors, if the two side monitors on the bottom were portrait, it would be easier to view their entire area. The fourth monitor would be landscape above the bottom center landscape monitors. If the aspect ratios allowed you to present what you need and in four screens, I expect this would be a very effective setup. But I need to see six screens worth of data for the way I trade. I want to be able to scan and not have to click to view anything. Note: the bevels add to 2.5". If smaller bevels, the top 1/3 of the upper row would be easier to view. Note: although LCD they do produce significant heat.
RE: Just a small suggestion: three 24-inch stacked on top of one another is gonna cause a major pain in the neck after a while. Sometimes one can think outside the box a little bit. Most of the multiple monitor stands are designed to set on top of the desk surface. I have 3 monitors actually mounted below the desk surface - just use a mount bracket to bolt to the 2 vertical side panels of the desk (built with fiber boards). These monitors can be swung out and tilted up to face towards me. They serve my peripheral vision. Looking down is much easier than looking up. In an office environment it may look a little odd. But I trade from home so it's no big.
My personal experience was different. Although I could tilt the bottom and top monitors of the three to whatever I wanted, and I tried the stand at all heights from the desktop to the floor, the vertical spread was too much. It was easier when the base was below desk height, but not too low. The most usable was when the base was sitting around mid-tower height, usually on a small table. (went mobile to trade at a friend's place, to compare my two data feeds to his, with the stack sitting on a mid-tower - his daughter called it a play date) photos to follow
22" monitors here's the stack of three, sitting on a small table base of monitor in TV stand is at desk height - you can see the three dry erase markers left over from drawing trend-lines on a 30" CRT before I got a proper data feed