hard to say. large eucalyptus trees are hard to find most anywhere in nurseries especially in the PNW. in any case, they grow so fast normally that a happy and healthy one gallon plant can become 4' the first year and potentially twice as large the second year with corresponding growth for the years after. my suggestion is to consider doing mail-order from www.forestfarm.com (near grants pass) or www.cistus.com (near Portland) get a relatively small plant that with any luck will pleasantly surprise you.

FWIW, my suggestions for good trees for your area are gunnii, niphophila, debuezevillei, neglecta, parvula, and perriniana for starters as fairly hardy especially if planted in a cold wind sheltered area with good drainage. would suggest that you stay away from cinerea (often sold as "silver dollar gum" in the "herb" section at nurseries)as it may be a bit more tender in colder winters. hope this helps.