There are number of accessibility resources that are published by government and other agencies.
General Accessibility
https://visitseattle.org/visitor-information/accessibility/
Transportation
https://wheelchairtravel.org/seattle-wa/taxis/
https://www.portseattle.org/services-amenities/transportation-sea
Tourist Spots
http://www.seattlecenter.com/visitor-info/accessibility
Seatac Airport
https://www.portseattle.org/sea-tac/accessibility-at-sea-tac-airport
https://www.portseattle.org/services-amenities/transportation-sea