Spacing? The smaller azaleas and rhododendrons can be considered a groundcover. That's the way they grow naturally.
There is nothing wrong with letting them grow together rather treating each one as a specimen.
Mike

Despite the claims of Z5 hardiness, itea 'Little Henry' does not do very well in the northeast Z5 areas in my experience. (A good reason for including geographic as well as zone information when posing a question). If others have had success in your area, it will probably do fine.

'Haaga'is one of the super hardy Finnish hybrids, but, again in my experience, suffers badly from wind and sun burned leaves if not protected in the winter. (Some form of winter protection is probably a good idea in an east facing bed for any rhododendron - strong morning sun when the soil is frozen is very hard on rhododendrons.). 'Haaga' is relatively low growing, but doesn't spread out much horizontally. If that's what you're looking for there are better choices such as 'Ginnie Gee', 'Scarlet Wonder' or some of the hardiest ground cover type azaleas.

I've given up on Little Henry....it gets 18-24" tall before dying back again in winter. My two Haaga on the other hand, are 5' tall and still going. They are planted in a NW exposure and are untouched by winter's hardships.

Thanks everyone. I went with little Henry and Karens azaleas. Othe side got little lime hydrangeas. I'm keeping my fingers crossed about little Henry.

Sorry to agree with everyone else about Little Henry. I have tried twice and they dont make it. Along with my parents have killed one also. Only place I ever see them alive is at the nursery.