A 17 year old economy didn't have much sound insulation from the getgo. From what I have been told, Toyo's are about as quiet as they come.
That brings up a good point. Take a look at the car stereo enthusiast's pages, they rip out entire interiors and lay down this thick rubbery sound insulation stuff, mass loaded vinyl. On the outside you can spray on rubberized undercoating (make sure the undercarraige is thoroughly de-salted first!)
Another thing to consider is rubber suspension bushings. Hard, shrunken bushings will transmit more noise than fresh soft bushings. I'm not familiar with your particular car's suspension, I'm sure at least the front stabilizer has rubber end links and bushings, maybe the suspension has a big compliance bushing or the like.
I do have some Michelin LTX M/S2 tires on my work trucks and they are pretty low noise tires.Any advise on tread pattern to help me narrow down some choices?
Generally, straight treads with some asymmetry to the tread blocks and sipes are quieter. But... what matters as much is the R&D and quality materials. What you need is a tire where the tread pattern is chosen by the engineering, not the marketing department.