Chuck - Thanks for the info -
With respect to using poplar for the bench top, I guess I wasn't aware that it was so soft. I've been using the panels as a makeshift bench for a couple of months(sitting on sawhorses). They are a little soft, but I figured that they just needed a finish treatment.
These panels were just too good to pass up when my friend offered them to me - they are actually "seconds" from a shop that makes wood coffins - they were supposed to be the bottoms for the coffins.
Maybe I'll use them for cabinets like you suggested, or I was going to make a bench arrangement for my compound miter saw and my future RAS, so maybe for that.
I'm building a table with maple right now. I REALLY like maple, it works good, and has a great appearance. So I think I'll go back to using it for the workbench.
Thanks for your help -