The commute within 1/2 hour from South Plainfield will have to be by car. South Plainfield has relatively easy access to Rte 287 which is the closest major corridor that travels north and south. It's a bit more tricky to get to the GSP or the Turnpike.
Depending on your price range, there are several towns that can meet you commuting and schooling needs.
I can recommend New Providence and Berkeley Heights , Scotch Plains, Westfield , Fanwood and Clark, in Union Cty, all have high ranked schools. All have the semi-suburban look I think you are referring to as well as being close enough to South Plainfield without ever having to get on a highway to get to and from work (and definitely within the 1/2 hour commute time).
I am familiar with working with relocation buyers, and first time buyers too (if that's your situation), and since I work in these areas no need to use another agent for a referral.
Feel free to give me a call at 908-675-0167 so we can chat about what you need and I can give you more information. I look forward to you call.