I used an A-frame type stand for a little while with my Roland E-50 and Yamaha PSR-s910. I think it was the On-stage KS7903, except for some reason I only remember it having two tiers.

The most important reasons I chose this stand were: (1) it was sturdy, (2) the "spacing" between tiers was fully adjustable, and (3) the angle of the arms was also adjustable.

I don't play pianistically (and I'm not sure that's even possible with a multi-tier setup.) You will ALWAYS have some compromise. But having a comfortable reach to both sets of keys, and some visibility of the displays was important. I found that a slight angle actually made the black keys more accessible. It would have worked equally well for playing standing up. I also don't sing so I didn't need to worry about poking a mic through between tiers. If you need a microphone, a headset style might be the best type with this setup.

I had also intended to use my laptop for score display, page turns, and even MIDI sequences. The top-most tier would have been way too high to see or view seated, so my thought was to put it off to one side. I'm sure they make dedicated laptop or notebook stands for this purpose. I was planning to set mine on a heavy-duty Manhasset music stand, and I think I tried it once for size and sturdiness.

Sadly this versatile and powerful arrangement didn't last long. After 6 mos I decided that I wanted my dining room to look like a dining room, and not like an '80s Journey set. So I ditched the multi-tier stand, and upgraded to a Tyros 5 driven by a couple of special styles on a BK-7m placed subtly off to one side. This combo had most of the power of my E-50 / PSR-S910 duo. To visitors it probably wasn't obvious that I was using two arrangers. I chose the Tyros because it had a decently-sized built-in score display with page turns. So the most pressing need for the laptop disappeared too. I could have let the Tyros take over with a MIDI sequence at any time, and except for the absence of mistakes, no one would have been the wiser!

I'm sure others will have other recommendations but I can tell you from experience that it's possible to achieve an effective setup.