New Jersey is like Essex. It's not that pretty, lots of traffic, high property prices and taxes. It's basically a suburb of New York in the north and a suburb of Philly in the south. On the plus side, there's lots to do on the east coast, you'll be near New York City (or Philly), and the salaries are probably higher on average. The Jersey Shore down the east coast of the state is a decent stretch of beach as well.

Seattle is a very hilly town, where it rains a lot. The Pacific North-west is one of the most beautiful parts of the country. It is also near an Ocean. It's a higher quality of life in my opinion, though slower moving. There's loads to do there if you like the outdoors (esp. skiing). There's a pretty decent sized IT industry in Washington.

Both places are warm / hot in summer and freezing in winter.

I'd go for Washington between the two, assuming I was here for a long time, and had kids in tow.