Flying open cockpit I would wear one, also formation/aeros with a chute, just round the local area in a Piper etc I really would not bother, not so worried about other club members, but if I have pax it makes it a lot more relaxed if you make it as normal as possible, start dressing up in special gear will make most nervous pax worse, not sure if it would be more or less nerve racking if you also dress them the same.