We study and characterize social-aware forwarding protocols in opportunistic networks and we derive bounds on the expected message delivery time for two different routing protocols, which are representatives of social-oblivious and social-aware forwarding. In particular, we consider a recently introduced stateless, social-aware forwarding protocol using interest similarity between individuals, and the well-known BinarySW protocol, which is optimal within a certain class of stateless, social-oblivious forwarding protocols. We compare both from the theoretical and experimental point of view the asymptotic performance of Interest-Based (IB) forwarding and BinarySW under two mobility scenarios, modeling situations in which pairwise meeting rates between nodes are either independent of or correlated to the similarity of their interests.