We do a lot of picnics and BBQs, so are well equipped for both. As well as my newly-updated beverage case, we have a larger picnic case, fully stocked with melamine plates and cups as well as a cheery apple tablecloth. We even have two emergency picnic kits - one in each car Yep, call us keen!
My family would probably argue that I am the keen one, dragging them out in all kinds of (wild) weather for al fresco dining!
As well as the usual plates etc, I nearly always pack a tablecloth to cover dirty and/or graffiti-ed tables.
More often than not public BBQs are left uncleaned. We take a pack of BBQ wipes and a roll of paper towel with us. Nick cleans the hotplate before use - and again afterwards. I generally clean the bench surround as well.
We carry a few plastic grocery bags with us and use one for rubbish. (Since relocating to Victoria, we've noticed many parks have a "take your rubbish home" policy). Dirty plates, cups, cutlery and utensils etc are brought home for washing - in another plastic bag.