I think people use straws in restaurants because they are provided without asking. I don't always remember to say "no straw" when ordering a soda and when it comes with one it is too late. At the very least restaurants should be required to ask whether customers want one. Best to ban the altogether, though.
education is important, especially on issues like water quality. Many people still think that water from a bottle is safer/cleaner than tap water. That faulty notion needs to be addressed more aggressively by the City. If there are areas of Sunnyvale were the water quality is indeed not good enough that needs to be known and quickly changed. Bottle refill stations like the ones some schools have (e.g. CMS) can help a lot. I agree that social media should be used to provide people not just with a environmental but also an economic argument (if you do not use a bottle of water per day but a refillable bottle for 1 year you safe $XX, etc.)