+1
Gotta go with the weighted chins. This of course is taking for granted the fact that you are able to properly chin your bodyweight.
If I had a choice, it would be chins first, weighted chins second, and if I needed more--a partner to help with 'variable resistance' bb curls. I would concentrate on each aspect of the repetition...obviously accenting the negative and static portion of the rep.
If I felt I was able to recover, I would go to complete failure (or as close as humanly possible)--eat good, take a nap, eat some more and take another nap.
When the muscles were no longer sore (2 days?) I would pump the hell out of em' (no failure) and repeat the rest/food portion.
My overall bodyweight has to go up and my caloric intake must increase in order for me to gain any more size in the biceps.