jkleban - I'm curious about this now.  Under Preferences | Audio data there is a field for the Render bit depth that gives you only 32 and 64 bit options - this is apparently for not just freezing but "bouncing and applying effects".  But I don't know if that still applies for just a VSTi output "stream" that's not been frozen, i.e. is there actually bit reduction taking place when going to 24 bit.  
 
In any event thanks everyone for all for all of the replies!  I feel like I've properly 'vetted' my issue with the Cakewalk community :)  I think I can go forward now with the reasonable assumption that if my mixes suck, it won't be due to dither (LOL)

Anderton
The easiest way to hear what dithering does is to reduce the level of a piece of audio to -85dB, or whatever level gives you truncation. Then you can apply dithering and hear the difference. I did an audio example for an online webinar using an orchestra, and you could really hear what the dithering did. Realistically, few listening environments allow hearing those kinds of low-level signals but when you can, it helps. It's not something you "hear" as much as "sense."

Thanks for confirming my idea. I've heard what it does in situations created artificially to showcase it, but I have never been able tell any difference with real world use for my mixes.

jkleban
Me thinks that a 32 bit VSTi has nothing to do with audio depth, rather the code running as 32 bit 

Absolutely correct. 64-bit plugins can address more RAM. They also could, conceivably, under the right conditions, be slightly more efficient than their 32-bit siblings (the converse could also be true). In terms of sound, though, 32- and 64-bit versions of the same plugin will sound exactly the same.
 

I think I can go forward now with the reasonable assumption that if my mixes suck, it won't be due to dither.

Very wise conclusion, David. It also won't be because you haven't spent enough money on plugins yet.

bitflipper

I think I can go forward now with the reasonable assumption that if my mixes suck, it won't be due to dither.

Very wise conclusion, David. It also won't be because you haven't spent enough money on plugins yet.

I know this to be true as I have tested it empirically over the course of many years ;)