For those of you who offer onsite support I wondered if you charge a day rate or just your hours worked.

I will be offering conference, seminar and committee administration and will offer on site supprt (depending on location). If I am administering a conference and my client wants me on site for registration, meeting and greating and general smooth running, I would be very happy to do this.

However, I'm not sure how I would charge for on site support or what people do generally. If I am travelling then do I charge for the travel time as I may not be able to work with other clients during this time and I certainly won't be able to do other client work during the time I am at the conference.

I thought perhaps a flat day rate plus expenses would cover this and wondered what other people do. Do you base your day rate on so many hours (8 or 10 perhaps) or do you charge for your travel time plus hours worked.