I completely understand what you are saying. Initially I had tall bearded iris in the back, then daylilies in front of them. It looked good on paper! And the first year, it worked great. But I just spent a part of my summer separating my iris from daylilies, now they are in "solo" beds, and I have a feeling that both will be much happier over the long run.
I know you have mentioned that your gardens are terraced, and perhaps if I had done something similar, the TB/ daylily bed may have worked out better.
I also have hosta with coral bells, and yanno,l that is not working out so well either, the hosta are overpowering the coral bells. Just yesterday I was thinking about "separating" those two next year - but then I will have yet MORE solo beds......
I think your idea of terracing, or otherwise having them together, yet separate is probably the best idea, perhaps for those of us like myself (and you?) that don't seem to be able to figure out how to truly mix different perennials and have a more carefree, cottage garden type look. ~Jan
