I did 14 last year Jen will probably do the same number this year and I do them in 3 sizes, family, couple and individual, i divvy the items up according to taste and in terms of numbers it is usually something like:
Family
3 booze, 2 jam, 3 chutney, 7 confectionary, 3 baked goods, and all three spice mixes, so approx 20 items
Couple
2 booze, 1 jam, 2 chutney, 5 confectionary, 2 baked goods and all three spice mix, so approx 12 items
Individual -
Slightly more tailored as BIL is dairy free and GMIL doesn't drink but tends to be about 8 items from the list. I also use slightly smaller jars as no one wants to be ploughing through the same chutney/jam for weeks on end!
Not sure how I will divvy up the pickles, as they are new for this year, but you can be sure my grandmother has her sights on a large jar of pickled cauliflower!
Of course if there are bits and bobs left over I just add a few extra things here and there.
I also create a book with blurb.com, with a round robin letter, photos from our year and a load of recipes either to use with stuff from the hamper - e.g. what to use the herb rub for or cocktail recipes for the booze. Or just new recipes we have enjoyed from this year.
Yes I realise I am a complease Christmas Jobs worth!