Seattle-Tacoma International Airport (SEA) is the recommended airport if flying in. Sea-Tac is the standard airport when flying into Seattle, and it is ~30min drive to the wedding venue in Renton.
Renton is a large suburb of Seattle, best navigated by car. Taxis and rideshare services like Uber/Lyft are generally available. If interested in further exploring Washington, a car is recommended. The Link Light Rail is available between the airport and Seattle and there are buses available around Seattle and between the airport and downtown Renton.
Consider accommodations near SeaTac or in Renton, Maple Valley, Issaquah, Covington, Newcastle, Bellevue, & Seattle. Feel free to reach out if you want more details about a particular location!