Clocktower would be a great option since they are local for you. You can always ask to speak with the manager of your local coffee shop. Often when I am in Peets I will ask them if they have any grounds to take away. Depending on the time of day you can get a ton (almost too heavy to carry) or very little since they just changed out their garbage bags. Usually they are very accommodating. Also if you want a more regular pick up time you can arrange with the manager to drop off your own bucket (I would use a 5 gal. bucket) and they will fill that and save it for you. The next time you come in you can swap out for a new bucket. It depends on the coffee shop but usually you can arrange something that works for everyone. Sometimes the coffee you carry away can be very heavy so the bucket idea works well and is easier to carry plus you wont have any possibility of dripping or spilling in your car.
Usually any time you walk into a coffee shop they are willing to give you what they have but I find it is nice to have a relationship with your local shop.
Also watch out for plastic milk rings because sometimes they slip into the grounds. Otherwise you can compost just about everything else that comes from the coffee shop including filters.
I have found a noticeable difference in my compost when I add coffee grounds. I experimented for awhile on amounts but adding the grounds was the only time I got my compost pile to get really hot! Plus the finish of the compost was very nice as well.
Good luck!
~ Jennifer