Good question... the entire key is the type of owners you have in your league. In the league I've been running for 8-9 years with friends (from work, softball, etc.) I've continually tried to do things to make the league more fun... keepers, live drafts, etc... but there simply are a few guys who are REALLY into it and a few guys who play just to play. As a result, the league tends to run smoothly, but quietly with not too many trades and not much smack talk. A guy I work with is in a couple of leagues with guys who are fanatical - as a result, there is endless amounts of emails on rules changes, smack talk, etc. plus lots of trades, moves, etc. and with owners that into it, you can really start to add other things like minor leagues and make the league formats a lot deeper and challenging.
"The government cannot give to anyone anything that it does not first take from someone else"