I wouldn't be too quick to dismiss league play. There are some flaws in most leagues, but they also offer some pretty nice benefits. Even if you just play league for 2 or 3 sessions, you will get some pretty good competition. Don't worry about handicaps...just play your best game every time you get to the table.
You will have the opportunity to play many different players of different skill levels. Learn from every match you play.
The team format of leagues is very good to learn how to handle a different kind of pressure. Unless you are a total ass and don't care at all about your team, you will quickly realize that you aren't just playing for yourself, but for all your team mates. While this isn't something you deal with in tournaments, pressure is pressure, and learning to handle it is pretty important.
Practice time on league night is also helpful. You can match up with the better players on your team at the practice table, and learn quite a bit.
Those who automatically dismiss league play without considering all the advantages are missing out on a great opportunity to play a lot of different people under a lot of different circumstances. League play is what you make of it. If you think it sucks, it sucks. If you approach it as an opportunity to play, have fun, and learn something, that is exactly what you will get out of it. It's up to the individual to make the most of every opportunity to learn and improve.
Steve