Getting to the game:
Rick, since your family lives in Oregon, you probably are pretty familiar with Seattle? So you'd be more comfortable finding places to park than other visiting fans that don't know the city. So this is advice for all.
Unlike in some NFL cities, here you can park fairly close to the stadium. It's just a matter of how much you're willing to pay. Most visiting fans who aren't familiar with Seattle, but are going in a rental car might be more comfortable parking north of the stadium, where our downtown is. This is a little more expensive. Savvier fans who know Seattle well can probably find some relative bargains the same distance south of the stadium, or east (International District).
To be on the safe side, be ready to pay $30 if you're five blocks away from the stadium. There are lots that are a block away, or right next door. Those will be $50, maybe even more.
Not everyone is excited about paying that much. So here's some public transportation options:
Metro bus-up to $8 round trip, depending upon route:
http://metro.kingcounty.gov/up/spclevent/seahawks/
Sounder train-$7 round trip:
http://www.soundtransit.org/seahawks
Getting in the stadium: Even before the Paris attacks, security at NFL games was pretty tight. Everyone goes through a metal detector. You'll have to pull out your cell phone, keys, change, anything else metal. You'll have to take off your hat.
One thing that isn't always well publicized is the bag policy. Women can only take in a very small bag. Otherwise, no purse. And kids can't bring in a normal backpack with snacks, books, games, etc. Steeler fans who go to Heinz Field every year will know this, but fans out on the West coast who haven't been to a game in awhile may not. The only decent size bags allowed in are transparent, so security can see everyhing you have inside.
Stadium Food: I think we have pretty decent stadium food? Rick, you can bring food inside for your daughter. But, if she'll be happy eating chicken strips and fries, at least, Ivar's in the stadium has that and pretty decent fish & chips. The stadium hot dog isn't bad either. But the hot dogs outside the stadium, along with other food, will beat the stadium food. For fans on the Steeler side, you may want to pass on this, as the venders are on the home side, outside the stadium. If you are coming from that way, though, it's worth checking out. I'm partial to Joe's Gourmet Dogs (yellow banner).
Restrooms: Rick, if you need a family restroom for your daughter, section 118 is probably the closest one to you.
What to wear/what not to wear:
Steeler fans should be just fine wearing black/gold logo stuff. Jerseys?
I'd really stay away from these two: Ben, and Bettis. Ben especially. These two guys, more than anyone else, will bring back bad Detroit memories to the home fans. Steeler fans will get all kinds of bad comments about Ben if you're wearing that jersey. Maybe some about Jerome too....or you will have to debate the HOF worthiness of The Bus.
I'd also think about not wearing a Hines Ward jersey to the game.
But, that leaves a ton of others that no one will hassle you for wearing. Some could even start some good conversation. Troy P was also part of the SBXL team, but no one hates Troy. And he has the USC connection with Pete Carroll. And I don't think any of us are mad at Heath Miller himself for SBXL, just at the side judge that let him get away with holding.
No one hates Antonio Brown...Steeler fans will probably get comments about how good he is, and that we're wondering how Sherman will do in coverage against him. We don't have any beef with LeVeon Bell, either.
Lots of good vintage choices, of course...so bring your Mitchell and Ness Steeler throwbacks. Franco got his last cup of coffee in the league with the Seahawks. So if you wear a Harris jersey to the game, you'll probably have some nice talk going. No one hates Terry Bradshaw! The same surely goes for Swann and Stallworth. The blue collar part of our fan base will likely give props for anyone wearing a Bleier, Ham, Lambert, Hoge, or Greene (either) jersey.
Anyway, hope some of this was helpful to Steeler fans coming to the game. One more link:
http://www.centurylinkfield.com/stadium-guide/