I think you need to focus on getting a good vodka. That will make or break
your martini. I prefer Kettle One vodka.
I usually use equal parts apple pucker and kettle one with a dash of triple
sec.
Another great vodka that I found that most of my customers like in their apple
martini's is Absolut Citron. It gives it an extra zip.
Another thing you can try is to add a splash of pineapple juice. This helps
out if the drink is too strong for your guest.
But I'm not sure if you want to make an entire pitcher at once. I would make
each drink seperately. I don't think there's anything wrong with making a
batch of martini's at once..but that's just me.