I recommend the Novotel at crown or Rydges Lakeside. They are both at the edge of the city (different sides) but on the same side of the city as Manuka Oval, you just go across commonwealth ave and down Canberra ave to get to it. In relation to the airport again really simple down parkes way which turns into the rd the airport is on.
Both are very nice and with in walking distance to the city for dinner etc. I live in Canberra and am pretty picky ;-)