B/W 702 s3

I don't think the Rotel is a good match to the B&W's from my experience with the matching Preamp, I do not have the amp. Little lean sounding and a little bright, not overly musical either. I found the preamp to be neutral leaning to the lean, bright side, if the amp has similar sound, then I would look elsewhere for a quality amp. I would not bother with the tri-bi wiring or amping get a solid single amp to drive them. If money isn’t an issue do mono blocks. 

Adding a subwoofer should make a big difference. They are lacking low end punch. Bi-amp/bi-wire won't do anything to help the lack of bottom end.

Frequency reponse on those speakers is 46hz to 26khz, so, bass and thickness may be lacking to your ears...  Try pushing them closer to the front wall and farther away from the side walls.  This should increase bass and reduce any reflections present.  Also try toeing them in or out, depending on how they are currently set up. 

Note:  Usually for full range towers you want the low range frequency response down to approx. 21hz... so, as others have said, a subwoofer may be the fix. 

What don’t you like about them and what specific improvements are you looking for?  Also, what’s the rest of the equipment in your system?  I highly doubt bi-amping or bi-wiring is gonna transform what you’re hearing and will likely be a waste of $$$.

They lack punch, not the cute monkey either.  Compared to my older Carver/JBL set up, they need the volume very high to start to sound better.  I do tend to like a brighter sound and I listen to mostly rock and roll and a little soul.   Trying to upload an image of the set up.  

I am thinking about trading them in with my Focal Utopia micros for the Klipsch LaScala's. About the same money and seems to pair better with the Rotel gear