Sweet. I was right.
Thanks for the input, folks. I'm kinda with mr_X on the height issue--2 feet is good. My arms are right at about that long *lol*. Plus, if I start making the gallons climb, I'm going to get growled at.
Cost is one of those things that I considered, but it's doable. It's just going to be a very, very slow build, as I intend to get the final product I want to use the first time rather than trying to save a bit and having to buy a new one, so it'll be a while before I'm even ready for live rock, much less fish. I'm patient. Gives me more time to look at options for stock, corals, and aquascape ideas.
Still not sure what I want to stock other than clownfish and the royal blue tang, but thinking banggai cardinals, maybe some chromis, some sort of goby, some sort of blenny, some sort of wrasse... and a lot of mushroom and leather corals and pulsing xenia *lol* Nothing too hard. Maybe some Kenya tree and brain coral after I get some experience under my belt. We shall see. I keep looking at the mandarinfish and considering one of them for a few years down the road, too.
On the plus side, I did get permission to put in the 180 today, and we know where it's going. Just means the 55 gallon and the 46 gallon need to do some moving around, since the non-fishy people have issues with having two tanks in one room. But yay! I can start making solid plans, now.