[Group6]

So, when I'm building a speaker and recessing my tweeters and woofers, does the thickness of my front panel need to be the same as the lips my tweeters and woofers, or does that affect the sound at all?

[S Clark]

I'm not quite sure I understand the question, but the main issue is creating a smooth face on the front baffle.  If there are irregularities that the sound waves pass over, they create reflections and interference that will cause additions and cancellations at various frequencies.  Think of it like the ripples behind a stick in the water flowing past it in a creek.  This turbulence creates audible effects.  Even the edge of the baffle can create turbulence if not rounded.  See http://murphyblaster.com/content.php?f=cabinets.html
The author of this study is Dennis Murphy, a highly respected speaker designer and member of AudioCircle. 

Therefore, countersink the tweeters so that they will be even with the surface of the baffle.  Try not to leave gaps between the tweeter and the wood.  Counter sink the woofer as well, although the bass response is not as affected by diffraction issues as the tweeter.