I'd live close to work and rent while you get a feel for the city, especially since you don't have kids. Queen Anne, Magnolia, Interbay, Ballard, Fremont, Greenlake, Wallingford and Ravenna are all nice neighborhoods that shouldn't be too brutal to get to South Lake Union from. You should be able to find a little more room for the dog in those places than downtown, SLU or Capitol Hill.
If you like Seattle and want to buy, you should be able to quickly save up for a down payment with those salaries. No rush to buy though. The local housing market has probably peaked and it's definitely become more buyer friendly the last few months or so. And I'm not sure what you're looking to buy but 450-500k might not go as far as you'd think.