Thanks for all the input guys. I've taken the suggestion and tried to rule out all the other stuff (valve covers etc). I just don't see any sign the leak is coming from anywhere but the intake. However, I did tighten the valve covers down and it did seem to slow it down but it might be in my head.

Assuming it is a slow leak at the intake, do I have any other choice but to R&R the intake? Is it possible to force some RTV or other sealer into the corner to stop it? I know this is probably futile but if it would save me a weekend of work, I'd try anything at this point.