A small thing I thought of. When you gift someone something they like, if it's silver or gold quality they should appreciate it more. something like, silver= +30% gold= +60% Now people will be giving their best to their special someone on their birthday or what-have-you. Another small thing, say you give someone the same thing two times in a week. Maybe it isn't as impressive anymore, so it counts -30%, which persists until you get them something different. This will make befriending people a little more difficult as you need to find two things they like for maximum benefit.