The Portland airport has a bike assembly room on the lower level near the baggage claim. It has a work stand and tools are available to check out free from the visitor info booth nearby. Here's some info for bike access at the airport. http://www.portofportland.com/pdx_bcycl_trnsprtn.aspx

I'll second the Reach the Beach route.

If you find that you have to cut a couple days of riding you could fly into Eugene and ride to the coast from there.