In german the position of an adversative particle has a crutial effect on the sentence: It defines the phrase on which the author of the sentence wanted to put the focus on.
Er runzelte die Stirn, sie aber sagte noch nichts;
Here the word "aber" comes immediately after the word "sie" and therefore the focus on this word changes the meaning of the sentence: in this case "aber" as an adverb means that something does not meet the expectations, so "she" always
says something immediately when "he" does a frown, but in this case she does not. This sentence also might let you expect that someone else does instead of her.
Er runzelte die Stirn, sie sagte aber noch nichts;
In this sentence the word "aber" comes after a verb, so the focus is on the action itself, so in this case "she" still does not meet the expectations by not saying anything, but unlike the first sentence it is not the most uncommon thing for her to do. The second sentence also might leave it open if she doesn't do something else instead of saying.
Der Lohn ist karg, doch genießt man die abendlichen Stunden;
"Doch" as an adverb is used to explain a certain fact / action or to initiate a contrast the same way as "dennoch" does. In both sentences the word "doch" is used initiate the subordinate clause which is a contrast to what has been said in the main clause. The focus is set on the contrast itself, so the fact that people enjoy the evening hours is shown as very uncommon for people with low wages.
Der Lohn ist karg, man genießt doch die abendlichen Stunden;
"Doch" after "genießt" may imply that the action itself (for example sitting together and drinking something, which is not mentioned here), that the people mentioned do, does not really differ from what people in general with low wages do, but in contrast to these, the mentioned people do enjoy what they are doing.
To sum it up:
Formulating the exact differences can be very hard or sometimes even impossible, but in the german language the place of an adversative particle can have influence on what the auther defines common and what not. The "right way" hardly depends on the context of the sentence, the message the author wants to transfer and the expectations for certain actions to happen.
I hope I helped a bit finding out the clear differences.