We went on our first self-catering holiday last year since having kids and on the way back talked through all the things we would have done differently with hindsight, what we wished we'd taken and what was a waste of space etc. Dh wrote it all down in his notebook. The notebook is lost.
I have a day and a half to pack and the only darn thing I can remember is to take a jar of mixed herb sort of things to perk up pasta and omlettes etc.
So - as it says really! What do you take or leave?