Standard desk/table height is 30 inches or so. I have two commercially bought tank stands. The 21 inch tall 58 gal
sits 31 inches off the floor and the 19 inch tall 29 gal
is 29 inches off the floor. At this height, the tanks are at perfect eye level when seated - that's how I usually view my tanks anyway.
I built my 15 gal
stand so that the tank is 52 inches off the floor - it's bolted into the wall for stability.
For safety reasons, I would make your stand no more than 32 inches high. Otherwise, it might be a top heavy tipping hazard - unless you lag-bolted the stand into your wall studs.