I agree with a number of other replies that Lamai may be a good option. I live on Samui between Nathon and Bang Por. Nathon is a nice little town and Bang Por has a lovely beach with some nice restaurants on the beach. The area is quiet, so if that's what you are looking for the north west of the island may be an option. Although transport is not great and probably more expensive than where you are. You may need to buy that small car.
My girlfriend works at a hotel which is only a few minutes away from our cottage, hence our location. If we didn't have to be near her hotel then I'd probably move to Lamai. Everything is close at hand, bars, restaurants and the beach. It has a nice night market also and is easy to get about. Not as crowded as Chaweng which has a much younger feel to it. Maenam is also nice, with some good bars and restaurants but it's spread out over a large area. Bophut and Bangrak are also options for you. As previously mentioned, not many condos here, mainly houses, cottages and villas. Good luck with whatever you decide.