easiest settings for fill flash?

[canon_shots]

Hi everyone, I normally love playing with settings and experimenting, but my family and I are going to a big festival and I want to keep things as simple as possible. Will only have my Tamron 17-50 so no problem with variable aperture. Camera is 300D and flash is 580EXII. If I shoot shutter priority to meter for ambient, leave shutter at 1/80 to prevent shake at 50mm, and set flash for ETTL, will that to the trick? Conditions will be sunny to partly cloudy. The event is Polish Fest (in Milwaukee, WI) and I'll be trying to get mostly people shots, dancers, costumes, etc.

Thanks!

[Photon Phil]

Sounds fine but 1/80th might be a bit slow to capture much action IMHO. I would max out the shutter flash sync at 1/250 or close to that and boost the flash if necessesary. I know that things tend to move fast at the festivals.