We will be in Sienna for 21/2 days.We will have a car. We would like to do the Chianti trail,Orvieto,Lucca and SanGimgnano.Are any of these doable for day trips and is one town prefeable over the other for a first time visitor?

Thats a lot of whipping around in for only 2 1/2 days. Orvieto is not in Tuscany and too far for a day trip.

SG is an easy day trip from Sienna. It is pretty touristy but still fun to visit.

Not sure what you mean by the Chianti trail?

I would skip Lucca and do the southern tuscany drive to S'ant Antimo Abbey - also see Montalchino, Montepulciano, and/or Pienza.

Consider from Siena:

San Gimignano
Volterra
Colle val di Elsa (oh lord, how badly is that misspelled?)

You wouldn't have to stray far from Siena, you could see a lot. Siena itself is so loaded with great churches and other sights that you want to plan to spend time there, too.

How did you pick those places. Lucca and Orvieto are hardly feasible from Siena. I sugget you get a good map and stay in the Siena province--it would take a week just to see the highlights there.

I might suggest towns such as Montalcino, Cortona, Montepulciano, Pienza, etc.