Second display, refugium, please help

I'm FINALLY working with more space to expand my tank. I want to keep my 32 gallon cube as my main display. I want to add an expansion to it. Here's my options:

*20 Gallon Long ($50)
*20 Gallon Standard ($40)
*2nd 32 Gallon Cube Tank ($120)

I will build the custom stand. I already ordered things for the plumbing (hole saws, bulkheads, inside overflow skimmer). I will be making my first Durso overflow with a Mag 5 as a return.

I just don't know what to make. I wan't to keep my equipment (protein skimmer, heater, pump) behind a black divider and have a 2nd display up front. I was thinking refugium until I read several recent-ish posts talking about them being more of a hassle. I haven't kept up I guess. Has the community slowly stepped back from refugiums? Here are my options:

*Refugium
*2nd Display

I like the idea of creating a second enviorment with other species than my display tank. I initially wanted to simulate a kind of backwater system.

Any input would be appreciated.