I thought about that-- our house would be a horrible one for someone with animal allergies... although... I'd also be willing to shepherd someone in a hotel-suite if that is a preferable option. DD and I are actually quite good at going out into the world reasonably uncontaminated-- via showering and dressing FROM the dryer within minutes of leaving the house, basically and not sitting on furniture in the interim. This seems to work quite well for our friends who have severe cat (and dog) allergies.
We live within EASY driving distance to PDX, and all of the natural wonders of western Oregon; Crater Lake, the Oregon Caves, Shakespeare Festival, Bach Festival (though you've missed Helmuth Rilling, apparently, as he's retired finally), the Oregon Coast, and both U of O and OSU, not to mention Reed College and a host of smaller, less famous institutions. Oh, and for those who have reasonably high thresholds, there is also Burgerville. Yes, restaurant milkshakes-- even if you have PA/TNA. They are also quite good at accommodating egg and wheat allergy, and have no shellfish on the menu.
I want to also mention that OSF and several of the regional universities have competitive summer internships/workshop programs-- so for teens with particular gifts/interests, PLEASE-- be aware that you wouldn't necessarily have to send them alone with no local help on the ground.
I can definitely help a teen (or family) figure out safe(er/est) dining options or local/regional brands while here-- for the top 8, at the very least.