As a Seattleite who’s visited the other places a few times, I’d say you can’t go wrong with any of them. But you want details. Here are a few about Seattle:
Traffic can suck here, if you live far from where you work. But I’m not sure it sucks more than any big city. I ride my bike 15 minutes to my job, and it’s bike lanes the whole way. I can get around to a lot of the major central amenities in Seattle by bike (including with kids in the bike trailer). So I honestly don’t notice the traffic much. The city’s not considered as bike-friendly as Portland (fewer miles of bike lanes) but they seem to be making a real effort to fix that.
In terms of neighborhoods - based on my preference for living near where you work, it depends on your line of work. A lot of the tech-related jobs are in the suburbs to the east of Seattle (Redmond and Bellevue). They are like a lot of suburbs - generally more affluent, schools get better test scores, etc., but also afflicted with a pretty serious case of blandness (sorry to offend anyone living out there). They are also closer to country roads that are good for riding, as well as mountain bike trails.
If you’d be working more in downtown Seattle, or from your home, there are a lot of nice neighborhoods. North of downtown there’s Fremont, Wallingford, Greenlake, Ballard and Ravenna. Triathletes frequently gather at Greenlake to swim, or run on the path around it. Those tend to be the pricier neighborhoods. South of downtown there’s the Central District and Columbia City. In the process of gentrifying, with the goods and the bads that come with that. The school district has some real bright spots, but some real problems common to urban schools. So it really can vary from school to school. Chronic funding difficulties, schools in some neighborhoods that are dysfunctional and struggling to cope with the needs of lots of poor kids unprepared for school.
As far as the tri scene. My favorite shop is Speedy Reedy. Great people, great store. Another is Triumph Multisport. Not so near me, so I just don’t know them.
There are lots of triathletes and lots of triathlons within a 2-hour drive. The season fires up in June, when the water gets warmer. But the tri club scene seems a little anemic. Sounds like Portland has more going on with that. There are plenty of masters swim groups. A few groups do open-water swimming in Lake Washington a couple days a week from around June through early October. A couple running clubs, including one that has track workouts every week.
For tourists this time of year, a few fun things (weather dependent). Go for a walk/run along the waterfront in the Alki neighborhood in West Seattle. It’s one of the few parts of Seattle that actually embraces the waterfront. Or if you want trails, run at Discovery Park (you can Google these things to get details). If you like architecture, scope out the new downtown library. Very cool. If you like art museums, the Seattle Art Museum just opened in a new downtown building. You can see a stop-action car crash suspended from the ceiling. If you are looking for more funky scenes, a good place to catch local alt country/folk/rock is the Tractor Tavern in Ballard.
That’s probably information overkill, so I’ll leave it at that. PM me if you have any more questions.