I use about 3-4 pounds of frozen raspberries after 3-4 weeks. I let the raspberries sit for a week and then rack to secondary and let it sit for a few more weeks. The raspberry flavor is great.
What are some common fruits or sugars to add at this point? How about honey or brown sugar or something?
I added some raspberries, about a 2lbs to my apfelwein, just kegged it and it tastes amazing.
I made this recipe with pressed apple cider this fall from a local cider mill and it turned out amazing. The pressed apple juice comes through with a little more apple flavor. Give it a go, you won't be sorry.