And, oh yes: Both are serious Super Bowl contenders.
Listen to defensive back Brandon Browner when he says that Seattle "has big goals" this year after advancing to the playoffs last season, when the Seahawks defeated the Washington Redskins and gave the Atlanta Falcons all they wanted before bowing out in the divisional round of the playoffs.
Take heed when the pundits pick the Niners to win it all behind Colin Kaepernick, his bevy of offensive weapons and a defense led by Patrick Willis, the best linebacker in the league.
Add in the Arizona Cardinals, much improved because they have Carson Palmer at quarterback, a guy who can get the ball to Larry Fitzgerald. And don't overlook the St. Louis Rams. They think Sam Bradford is about to become an elite signal-caller, and their defense is much improved now that Jeff Fisher has had a year to settle in as coach.
To say the drama finally is returning out west after years when this division was a doormat might be an understatement.
"We have high expectations for this season," Seattle coach Pete Carroll told reporters during training camp. "We wanted to have a good offseason and we wanted to have a good camp, and I thought we did that. We're ready to go for the season coming up. I'm happy with how seriously the guys took things, and we're ready to try to take that next step."
Seattle and San Francisco are at the forefront. The Niners have Kaepernick, a talented dual-threat quarterback with a strong arm and eye-catching physical ability. The Seahawks have Russell Wilson, smart and compact and a great leader in just his second year. The defenses are two of the best if not the two best in the league.
There's even a local flavor, with former Utah State Aggies Bobby Wagner and Robert Turbin playing key roles as rookies in Seattle's resurgence last season. Throw in the fact that San Francisco came within yards of a Super Bowl championship in February, and the stage is set for what could be a memorable division race.
And it gets better. Factoring in the dislike these two teams have for each other could make it the best rivalry in the NFL.
In a year when the two franchises potentially could square off three times, Jim Harbaugh more than stirred the pot in June when he said the Seahawks "won by cheating" in response to a question about five Seattle players being suspended for banned substances since 2011.
Browner fired back, going on a Seattle radio station and saying he would put his hands around Harbaugh's neck if he were lining up against him after such a comment.
"I don't like using the word 'hate,' but it's definitely like a heavyweight fight when we play each other," Willis told ESPN.com. "We're not throwing little jabs that barely hurt. We're trying to knock each other out."
It should make for compelling football this season that no other division in the league can match. Each division has one team that's pretty good or elite. No division this season has two teams that are Super Bowl contenders, with great football and dramatic storylines as well.
That makes the NFC West the best in the NFL for 2013. And when it all settles, the Super Bowl trophy very well could rest in one of two cities with NFL teams that officially hate each other.
Seahawks vs. Niners
Oct. 18 • San Francisco 13, Seattle 6
Dec. 23 • Seattle 42, San Francisco 13
Sept. 15 • San Francisco at Seattle, 6:30 p.m. (NBC)
Dec. 8 • Seattle at San Francisco, 2:25 p.m.(Fox)