Sit in the right field seats for your best chance at a home run. Safeco is not known as a home run park, but left-handed hitters often litter sections 107-109 with souvenirs. Beware, though, as these seats will leave you exposed to the sun.
Section 103 is an alcohol-free family section, but it is not well protected from the sun.
Avoid 102-105 entirely if you want to see the scoreboard in Center Field.