Thank you everyone for the ideas! I was at the lfs today and I found what I needed. I went with red & blue columbian tetras. They are acclimating right now, but should fit into the mix nicely.
I still have some more playing to do with the plants, but I will try to get some photos posted this wk sometime.
With the current mixture of fish, the columbian tetras should fill in the mid level in the tank, which is what it was needing.
On a sadder note... it looks like my Oscar
is on her way out... there isn't anything more I can do for her. Due to the recent discoloration, it appears her kidneys are shutting down. I shouldn't complain, I've had 12 wonderful years with this fish... but I sure will miss her once she's gone. That will leave my 120 needing to be newly stocked, so I'm sure I will be back asking for ideas when that time comes too.
Thanks again to everyone...