I grew up in west Millbury. West Millbury's got a smug air these days because of all the 500K+ houses that took over the old farmland, but even the older homes are comfortably spread out, and there are still farms and orchards in operation. Millbury's population is a great blend of rich/poor people from all walks of life, although you will witness "small town cliques" between families who have been there for generations.
It is very close to both 146 and 395 which gives you an easy commute to Worcester. All of the schools were renovated in 2001-2004 and contain the latest in technology, and the library was expanded (3x as big) in late 90s. For better or worse, the new mall literally backs up to the middle school (Shaw).
Oxford still has that quiet, rural small-town feeling, with business development existing primarily to the far north and south of the town. They also built a brand new high school around 2003. 395 has three exits in Oxford which gives you a good commute to Worcester. I have cousins who live in Oxford and spent a lot of time there myself.
SMcD, I disagree that Sutton is cheaper to live in. Everybody I know who lived there complained of the higher taxes, particularly due to the town constantly resisting business development, and the real estate is very expensive for the area. It is, however, a beautiful town and worth the price.
Much of Worcester is getting pretty scary to live in, but southern Worcester (on the Worcester/Auburn town line) is comprised of cheaper residences with nice quiet neighborhoods. My grandparents have lived there since the 50s. Simply in terms of public schooling, however, I'd recommend an area town.