I often do on-site software training for my clients. When I do this, I typically bill a daily or half-day rate. My "half-day only" rate is about 65% of my daily rate because even though I'm only working a half-day, it's usually logistically impossible for me to see two "half day" clients in one day.
Recently I've had some clients asking for "an hour or two" of training (or other on site consulting), and they usually want it during the lunch hour. While it's only an hour or two, if I do it during the lunch hour, it effectively kills my day for any other on site work, and, woes me - the time to get ready and travel there and back - kills productivity for most of my day period.
How do most of you bill when a client wants you to come on site to work on something? Just for the actual time or do you have a minimum "physical appearance" fee? Do you bill for the time to travel to and from the client site? Do you have a sense of what the client expects to pay when they ask a freelancer to come on site?
Sorry if I'm over complicating my question but another situation I've encountered is a client asking me to come "for the day," but then only met with me a couple hours then dismissed me. Then I am start to wonder - will they be outraged if I bill for a day when we only worked a couple hours? I turned other clients away to set that day aside for them, but they probably don't see it that way...