Viburnum davidii would take years to reach that height but does get up there in time.

I really like Kalmia latifolia as a Rhody substitute, as it seems to like similar garden conditions and still has beautiful flowers. Very hardy to cold.

Don't know why rhododendrons are to be avoided in this instance, but I can guess - starting with foliage mildew, which is now nearly ubiquitous here and can even kill.

Unfortunately the kalmia is actually a bit of a fusspot in this region, despite the cool climate. Really good looking specimens are not that often seen here - even though Briggs nursery produces millions of them in Olympia.

In city and suburban gardens along its native Atlantic seaboard, it is one of the choicest tall shade plants. In country properties where it is spontaneous, it is a shrub that gardeners often handle as we of the Northwest do Salal (Gaultheria shallon) - as a plant to be lopped and sawed away until it forms a background for the garden one plants in the soil gained by this clearing. But in the Northwest, Mountain Laurel is not so eager; to grow at all well, it needs a woodsy moist place near a body of water or in the mountains

--Schenk, THE COMPLETE SHADE GARDENER (Houghton Mifflin)

I'm really sorry to hear that kalmias are fussy. I have had mine (minuet) for just over a year and I just love them.

I replaced my rhododendrons with winterberry. They are deciduous, but the berries are so bright and pretty and I find that the form of the leafless bush is nice also.

If yours look good, then you don't have to worry about how others are doing on other sites.