I live in a rural part of Suphaburi and love it. We travel around a bit and I know a few of the neighbouring provinces quite well.
Suphanburi city is just over an hour outside of Bangkok and is ok, the immigration department is excellent. It's mot too big but big enough for a Makro, Robinsons etc. and doesn't have the pesky monkeys that Lopburi suffers from. Ang Thong and Singburi are quite small, Chainat is ok and there's some fantastic scenery around there but again may be a little small.
The city I'd probably go for is Nakhon Sawan, if I were looking to live in a city, which I'm not. I don't know why but it always seems quite chilled to me with its beatiful park and Bueng Boraphet as well as some very nice temples.