I'm not quite sure whether you're after an explanation or examples. But here we go: “Now you're talking” - Meaning: said when someone makes a suggestion or offer that is better than one that they have already made - Examples: * "I say instead of staying home for vacation we go to Mexico." "Now you're talking!" * "We could just have some sandwiches for dinner. Or we could try that new Thai place." "Now you're talking!" “I wouldn't say no” - Meaning: used to say that you would like something that is offered to you - Examples: * "Would you like another drink?" "I wouldn't say no." * “It’s freezing, isn't it? Would you like a nice hot mug of cocoa?” “I wouldn't say no to that.” It hope this helps? J. Arthur

J.Arthur was quite right. You don't use those phrases in the same context. If you phrases that can be used in similar situations, then I guess that 'That's not a bad idea' is similar to "now you are talking" but less positive, and "I wouldn't turn my nose up at it" is similar to "I wouldn't say no", but is a bit more informal.