1. It's more useful to talk to people than it is to be an audience member.
2. A successful talk is one that produces interactions with people.
3. The grass is not always greener- the talk you missed was probably not as great as everyone is saying anyways (actually it probably was, but it's too late now...)
4. Picking only specific talks and people to hear can be a good strategy for avoiding talk burnout. Symptoms of talk burnout include napping in conference centre hallways, feelings of annoyance when you hear the same concept re-explained for the 10th time (which is probably because you're in the 7th Community Patterns and Dynamics session), and a desire to yell 'but what is your hypothesis?!' during talks (this may just be me). The only cure for this is to go have a drink.
5. Conversely, sitting through entire sessions can lead to important discoveries.
6. There are more areas of research in ecology than you can list: by bringing these researchers together, ESA is helping to foster continued growth in our field. Integrating all these bodies of knowledge is important if ecology is to be a healthy, mature discipline.
08/10/6:50, edited for clarity. #7 could be 'it's better not to blog while tired'.