E.L.
When we first started looking for a place to buy here my husband's uncle's primary advice was "Don't make him cross any bridges!" Traffic is nasty over the bridges, and with severe weather or a large accident it can add hours to the commute. I live in Bellevue and if my husband worked in Seattle we would probably try to move over there.
Find a house or apartment to rent in Seattle and get to know the area. There are some fantastic neighborhoods over there. Should you still want to be in an Eastside school when she starts kindergarten, Mercer Island has open enrollment, but then there is that daily commute again. :) There are a lot of options in the area. My advice is that you live close to work and then explore for the next two years while you decide what kind of education you want your child to have. There are a lot of school options too.