I hear you man... we moved into our current house over 3 years ago and we haven't completed all the things we set out to do. It takes time.
I have worked this weekend in a new addition to the system and I wanted to get some feed back during the testing stage.
I emptied the little space under the stairs and made it into my 2nd wet room. I used to have the RODI reservoir there only, now I added a refugium and a 70 gallon stock tank. After some thought I decided to go with the stock tank as a Remote Live Rock / Sump, because it will increase the total volume of water of the system (close to 190gl) and it will provide me with plenty of space to add live rock. I will also be moving some equipment there like the second fan and the second heater.
It will also free up some stuff from the 1st wet room where the skimmer and 30gl sump will remain. I haven't connected it to the main system, still looking for leaks and trying to figure out weak points.
Right now I use a MAG 9.5 as the return, a WON 600gph internal pump to feed the chiller that outputs into the refugium and a MJ600 to feed the Carbon reactor.
The idea with this addition is to run all of those things off one external pump. As you can see in the picture I am using a Reeflo Dart as the main pump. This pump will feed the Chiller, the Carbon reactor, the refugium and the main tank. I also left a couple of outlets available in case I add things later on such a UV lamp or frag tank. The pump will is rated for a max output of 3600 gph, way too much for the return so what I will do is to throttle it back with a valve, but I also have a T prior to that valve that outputs back into the sump just in case I need to reduce back pressure.
From the main tank the overflow will go to the 30 gl sump with the skimmer, and from there it will go into the 70 gl stock tank.
I will also have to redo my ATO because with this setup, the 30 gallon sump that holds the skimmer will have a constant level and only the 70 sump will lower with evap.
I will have to move one of the DC8 to this room. Either that or add a 3rd one!

(toys!!)
The refugium will be fed from the pump through 3/4" pvc, go into a SCWD and into 2 LocLines at each side of the fuge. The Fuge will overflow into the sump. This way the output of the fuge (pods) will go through the Main display before it reaches the skimmer.
I am considering the option of using a Y and connect the output of the chiller into the return line, that way it might be more efficient, otherwise it will go into the 70 sump and eventually get into the main tank.
Any ideas? Any thoughts?