Great option if you don't want to be downtown
We were in between houses, furniture in storage, and needed 6 nights in a hotel where we could cook in and avoid eating out every day. The Residence Inn was a good choice for us, but our stay coincided with the really bad construction mentioned by other reviewers. It can only get better and the South Lake Union area is great. We walked along the water and also explored the new shops and restaurants by Whole Foods, as far as we felt like walking. The trolleys weren't running due to the construction but I think they are now and that's all you'd need to make an easy trip all the way downtown.
We had a spacious, attractive room for the 3 of us (King bedroom) and a more than adequate kitchen. The sofabed was not great, but the king bed was extremely comfortable. They try hard with the breakfast, offering lots of choices, but I'm not a fan of their fruit-- melon or pineapple soaked in some kind of preserving liquid instead of being cut up fresh every day. They serve a huge number of breakfasts so it isn't surprising that the food is mass-produced, probably off-site. The public spaces were well maintained and the front desk staff was always great. Because we were moving we had all kinds of stuff with us and managed to forget 2 filing boxes with important papers. The hotel called me immediately so we could retrieve them.
The parking garage was scary (tight spaces, very steep ramp and expensive) so we parked in one of the lots across the street. Keep going until you see the signs for Daniels Restaurant parking. It is the cheapest, although the unpaved lot was dusty and our car got filthy. Totally worth it, we saved at least half the cost of the hotel garage.
If you're new to Seattle, you might want to stay downtown, but for a different take on the city, staying in South Lake Union at the Residence Inn would be a good choice.