Just FYI I think some people are describing what they do with their back (get an arch or not) and some are describing how they press the bar (to arc it or not), you might clarify your original question.
Personally I am not super flexible so my back arch is pretty limited but I try to do something with it, I am actually working more on my set up now.
In terms of bar path I definitely arc the bar back up, bar will touch around nipple area or just below, and head up and back to finish over lower part of clavicle. Elbows tucked on the way down, flare and slight internal rotation on the way up particularly after first few inches of the press. I have reasonably long arms so my bench press stroke is pretty long. The vast majority of people I have seen do better with a press that involves an arc, the longer your arms it is likely to be more pronounced.