Great Stay/Convenient
I was a little nervous about booking a stay at this hotel after reading some of the other reviews on tis & the travel site I booked through. I noticed on tripadvisor that the manager had responded to some people's concerns and I was impressed by that. It showed they cared. So I went ahead & booked it.
I took the train to Seattle to see the King Tut exhibit & was spending the night before continuing on to the San Juan Islands. The shuttle to the ferry terminal in Anacortes leaves from the airport & I was looking for something close by for my early morning departure. I didn't want to spend a lot for a hotel room for less than 24 hours and I wanted something convenient. The Clarion fit the bill perfectly. 
It is literally right across from the airport, but so soundproof you wouldn't know it unless you looked out the window!
I took the light rail from downtown Seattle to the airport stop, it took about 35 minutes. When you get off light rail you walk across a sky bridge, then go down to street level & walk about a block to the hotel (technically it is across a parking lot, but there's a car rental place & fence stopping you from walking directly across).
Check-in was very quick & the staff was very friendly & fun, making me laugh at the end of a long day. 
The room was very clean, although the colors were a bit dated (I'm not so much a fun of the 70s earth tones but others might like them). 
Amenities included vending machines, pool, exercise room, cable tv.
There is a restaurant on-site with very friendly staff. I had the best BLT I have ever eaten (try it on rye!).
Unless you are really out of shape, it is a short walk back over past the light rail stop to the airport terminals. However, there was quite a thunderstorm going on the morning I was checking out & the hotel offered a ride over in their shuttle. It heads over to the airport every 10 minutes.
All -in-all, I had a great stay & would deifinitely stay there again.