I know everyone's going to shoot me, but I had a great time at medlink. Of course merely having the name on my application form didn't help me get in, but it gave me a lot more ideas about the sorts of things I needed to be doing, and for the first time in my life I met large numbers of people who didn't dismiss me out of hand for being clever, and who had similar interests to me (I'm the only one from my year at school doing Medicine). Maybe I was a fool to fall for it but I found bits of it pretty inspiring, as someone who had very little proper medical exposure at that time.
Yes, it's expensive and yes, if you have access to other conferences they're probably good too (I went to Medlink back in 2000 so I have no idea if these other thingies were even running). But I really enjoyed myself, and without getting drunk either!