90g 4 foot upgrade to 125 6 foot, is it worth it??

[The Codfather]

Just a thought, but if I was looking at an upgrade, I would get the largest tank possible for the area I had. That being said, you figure a 180 is too large, is it the 24" width that's the problem? If your limited to an 18" width, aside from getting a custom build, your getting to a limited amount of tanks available.
A 72" 135g is already 24" deep, I think an option is going longer to an 96". If this is not an option, this tank might be the size your looking for. There is nothing worse than upgradeing just to realize you should have gone bigger. Just remember your going to increase your volume by 1/3, this is going to increase your costs as well in the future for maintainance, as well as a possibility of equipment upgrades.
Just my thoughts. An upgrade is good, but a lot of work comes with it.