I am 65 but active.I am backpacking in the midwest and northwest area. I am a vegetarian. I have kept two and half days in Seattle. Can anybody suggest an itenrary for seeing all things worthwhile?

For a solo trip to Seattle, how about the HI Hostel?
http://hiusa.org/seattle/
You can cook your vegetarian meals in their kitchen.
The hostel is within walking distance of the Amtrak station if that is how you want to arrive in or leave Seattle.

Will you have a car? And will this be in August or February?

no car and the trip will be in October. If I say i will be on a shoestring budget that would be an overstatement. Only silver lining is my vegetarian food is so cheap and I am a light eater. I dont know how to cook and that is a bit on the minus side but then the time I save in cooking and devote to reading.

sorry replace 'and' by I

For $31 you could buy a Hop on/hop off two day pass that runs a loop around the city all day... that gets you transportation to and from all the major attractions plus the history and commentary... We used Grayline...