75 gallon over 90 gallon !

I went with a 75, with a 90 you wont really notice that much of a difference, just get larger sump! plus then the lighting will penetrate more and like you said it will be easier to work on, especially if you build a 36" high stand like I did. The taller stand will make it much easier to look into the tank, and make the tank look bigger.

 

i would go with the 90. the added height isnt enough to mess with light penetration too much but gives the tank that "show-quality" feel. I like the L to H ratio much better on the 90s. Plus, you can put a taller canopy on a 90 and have it still look great. Also with the larger water volume you will be able to add an extra fish or 2. Oh and just stack your rock a little taller
EDIT: i am 5'1" and can just barely reach the bottom of my 90 gallon using a step-stool, with the canopy still on

 

When it comes down to it, you only gain about 10 gallons. Really isn't much.

 

The 90 is awkward to work on, tougher to aqua-scape and needs more light. I'd go 75. If you want more system water, just go with a bigger sump.

 

WOW, you guys are really making me think now, the 75 is sounding like a better fit.

 

I am 6'-4" tall, with a 6'-9" wingspan. I have a 26" deep aquarium, and when I upgrade, I am having a tank custom built to 20" because I hate getting my armpit wet when I have to get to the sand. Slightly less depth is not going to make a huge difference. I'd go with the 75, due to easier maintenance and less powerful lights for penetration.

 

I just upgraded to a 150 tall. 30" from my 90 that was 24" tall. I like the big view window that it gives. Yes it can be a little more work getting to the sand. But isn't the View why you have the tank in the first place??? I'm a diver and all the reefs that I have been on run vertical as well as horizontal. It is going to be what makes you happy. 24'' isn't that far to the bottom.

 

you also might want to consider the need to have more water, etc for water changes & top-offs for the larger system. When I was upgrading my 55g I decided that I was comfortable with my maintenence & water making routine so I went with a tank that was only a little larger but a different dimension, so it felt different.

That way I stayed on a similar regimen of water making each week & it wasn't a huge pain in the butt.

You may want to look into cube tanks, I absolutely love mine and the different dimensions: Saltwater Critters, Reef Aquariums & Fish Supplies, Saltwater Products & Accessories - Perfecto & Marineland Reef Ready Tanks

 

but what is the depth of the 150tall? The problem with a 90g IMO, is to use the height, the rock work needs to be too steep. I have a 93 cube and the depth itself isn't the main issue, although, certainly the height makes certain tasks more challenging, but the main difference is there is enough depth to have a gradual incline for the rockwork. In a standard 90, I think it tends to be more wasted space.

 

I'd still go with the 90. I, too, like that "show" look to a larger faced tank. Dont much care for long, squat tanks. My own opinion.

Lighting can be overcome.