Looks good but if you want something more narrow, perhaps some Rotala Magenta (macrandra narrow leaf) or Aponogeton crispus 'Red' would fit the bill?
Edit: i guess the latter is hard to come by in the US, so scratch that one.
I think rotala mageta might look too similar to the rotala colorata and rotala macrandra. I'd kinda like a different leaf shape. Aponogeton crispus 'red' is one I haven't even considered. It's not a stem though, is it? I'm kinda wanting something that will form a background bush.
I'm considering alternanthera reineckii but I've kept this one a few times before and the pink color is so intense I'm afraid it won't blend well with the other colored stems I have. I'm also still trying to get the hang of getting the rotala macrandra healthy. It seems when something does get out of whack, it declines in healthy pretty rapidly and takes a while to recover. I just need to make sure I'm staying on top of things and make sure I am always meeting its needs.
The tank looks like a complete mess right now. Lol. There's not really any organization to anything. Hopefully I'll change that before too much longer.