I wouldn't go for gourock, my parents live there and it seems more out of the way than it actually is. That said, it does have some lovely houses, though mostly up hills, and a small Main Street with nice cafés etc. I don't agree with the ex industrial description, that applies more to Greenock. There are lots of lovely villages nearby though- Houston, bridge of weir, quarriers village, Kilmacolm. They're all quite out of the way for Helensburgh and Oban though.
I would start looking at the corridor to the north of the river from the erskine bridge, from Dumbarton to balloch to Helensburgh itself. Luss is lovely and has a small village school. Loch traffic can be a nightmare in summer. Gartocharn, drymen, balfron etc wouldbe nice too. Helensburgh is a lovely place to live, with good schools, easy access to glasgow. In Dumbarton you'll get more for your money but it is very post industrial. Schools are average I would say. Balloch is a nice tourist town, but not much different to Dumbarton, it's just prettier. Five minutes from the tourist track there are some pretty awful estates.
I live in this area, feel free to pm me if you have any questions about specific areas or houses.