What time of year are you going to be here (sorry, I don't know when soccer season is)?
Big Rock Garden would be a nice place - large variety of maples and wonderful statues tucked in here and there - there are place to sit and rest too.
You can pick up a map at Viking Union and do the sculpture tour on campus at WWU. This would be a longer walk with less places to sit.
You could pick up a cheese picnic at the cheese shop in Fairhaven and drive down to Boulevard or Marine park - very easy (flat) walks - and watch the water and boats.
If it is raining and your Mom like movies the Pickford is great - bonus if the movie is showing in theatre one you can take wine in with you.
If you are here "in season" there is also a nice selection of boat tours - but I don't know if their schedule would work with the soccer game schedule.
You could drive up to White Rock for lunch (or dinner) we do that a lot in the summer. (don't forget that if you are taking your daughter that you technically need a signed note from the other parent if you aren't the sole guardian - if that is the case then you need that paperwork - they usually don't ask for it, but better safe than sorry).