I have some tinny, thin sounding audio that I woud like to sweeten a bit from within Vegas. Anyone point me to the proper Vegas audio tool that would beef up this audio?

Graphic EQ-pull a bit of top out and add a bit of bottom end (bass and mids) to taste. This is of course subjective dependent on ones speakers and how they're set and one ears. I find as I get older I have to spend more time and ask my wife for her opinion when I work on some audio.
I've also been using the NewBlueFX audio plugins and am quite happy with them. They help a lot in conjunction with the Vegas plugs.