@boomerang,
I thought I posted this earlier, but it was hidden behind some other stuff on my computer screen -
I just found their very small tree list..
http://www.portlandnursery.com/plants/docs/trees/Trees_Under_15_Feet.pdf
I like smoke trees (Cotinus coggygria) myself.. There's one that has blue green foliage shaded purple with large deep pink puffs, orange and purple red fall foliage - that's Cotinus 'Grace'.
It's neat that Fall is upon us soon - me, I'd go to the nursery and lurk until I figure out what I'd like best. Bring a Sunset Western Garden book with you, or the Nursery probably has one for use at the desk. It sounds from here (far away) like they know their trees there...
I had seven washington hawthorns in front of my last house - they are pretty elegant, have good form when pruned, have fall color and shiny red fruit - but I think they are too tall re what you are looking for.
I had two nifty trees I'm wracking my brain to remember the name of - I'd never heard of them before moving to humboldt county, so unless I just trip over the name, I guess it's lost in the universe.
I loved my Cornus capitata, but it's a no for your zone, and probably too tall in any case.. but Cornus kousa could be a go. C.k. 'bonfire has bright red fall foliage