I agree that Friday would probably lead to higher attendance, especially for a topic potentially appealing to a relatively wide audience. A photo walk in downtown San Jose sounds like a great opportunity to pick up pointers, as does hands-on instruction the form of a processing workshop (especially if we can process the photos taken during the walk). If there isn't enough time to track the process start to finish, either of those would be a useful exercise. As for other workshop topics, I'd predict that there would be interest in either working with Photoshop for general art (fanart?) production, or a workshop on drawing and designing with vectors. I don't know about others, but I'd definitely attend any of these workshops with >80% certainty.