The correct way to get from Key Arena (1 Ave N/Republican St, northbound) to Seneca St/4 Ave, westbound is:

* - 1 Ave N
L - Mercer St
C - W Mercer St
R - 2 Ave W
R - W Roy St
R - Queen Anne Ave N
L - Denny Way
R - 1 Ave
L - Broad St
R - 3 Ave
R - Stewart St
L - 1 Ave
L - Pike St
C - E Pike St
L - Bellevue Ave
R - E Pine St
R - 15 Ave
R - E Madison St
R - E Union St
L - Seneca St
S - 4 Ave

got it?