Please take special consideration to the side pane thickness. Once you make the decision, your stuck with it.

I would recommend 3/4" sides.

Best of luck. :)

The tank builder says that 1/2" Acrylite GP (12mm so actually 0.47") will only deflect 0.09 mm on the front pane and 0.03 mm on the sides. Not totally sure how they get the deflection numbers.

I might just ask them to build it with 3/4" acrylic. I like the look too.

I once really considered Acrylic myself. I seem to recall in all my reading about tanks in that size range, people said to go with quality material (your builder is using it) and to go 3/4" when dealing with panels that long. There will be some bowing no matter what but minimizing that is key plus the tanks end up looking way nicer with the thicker material in my opinion. The beauty of Acrylic is you don't really need to worry about your back too much when weighing 1/2" vs 3/4" options.

Acrylic Quality
 

What makes for a quality acrylic?

Based only on what I've read, certain brands have better strength. I can't say whether that's actually true mind you.

Second paragraph: http://www.associatedplastics.com/acrylic.php

I've always read good things about Acrylite GP.

Edit:

A ton of my reading was regarding Envision Acrylics. I was close to ordering a tank from James a really long time ago.

http://www.envisionacrylics.com/aquariums.html

This guy seemed to know the material VERY well. And he always used GP.

Yeah I want 3/4 even just for a look but the price increased 40% from 1/2 to 3/4!

Is 3/4 acrylic really that much more expensive than 1/2?

Prices
 

It is quiet a bit of jump in price when going from 1/2 to 3/4!
Where are you getting your quotes from?
I've dealt with plastic works in surrey on 86 ave and they have the best prices I've seen by far! One of the employees (Peter) actually used to make aquariums so he's got quiet knowledgable about aquariums

I think they have a different name now but yes, dealing with Peter :)

I dont think so. It's still plastic works. I was there couple days ago!

Different Peter then. Place I’m dealing with is Archer Plastics.