My 90 gallon is on a 6" high frame on a 28" high dresser (34" to the bottom of a tank that itself is 24" high) right next to the computer I'm writing this post on. I can turn and look into it, or stand up and look down into it. I would not want it any lower.

My 70 gallon is built into a closet in the living room and sits on a 36" high kitchen base cabinet. That one is really good for standing in front of, but shows more water surface than usual when sitting down across the room and looking at it.

Both have about 4-5" of substrate, and both are framed so that only the top of the substrate shows, so that raises the "bottom" even higher.

TW