My 1998 GS 500 was running great.  Then it started running not so great and I noticed some fuel dripping onto the starter cover area.  The bike now runs choppily and surges and sputters at lower speeds, but seems to be ok in the upper revs.  I did a little video investigating and found that the leak is from the air vent on the carbs... (http://www.youtube.com/watch?v=VZReZ-G3wdo&feature=plcp) ...

I suspect that this leak is not the real problem, and it really sounds like the carbs are flooding for some reason - cleaning? stuck floats?  I've tried the hammer tapping and nothing changed.

I really don't want to take the carbs off if I don't have to, so I thought I'd see if I was at least on the right track before I dove into that.

I think you are on the right track.  It sounds like the bowls are overfilling.  Might need to replace the needle valves, or maybe just the o-rings on the seats.

I started taking things out and cleaning them and putting them back and rechecking the flooding.  Now, it doesn't flood anymore, BUT it now runs rougher than it used to and I had to turn the idle up to keep it from dying.  I also cleaned the air filter (KN Lunchbox), but I don't think that would change the roughness too much.