Lots of interesting points in this thread. The two the stood out to me were, their usefulness is determined by project scale and by what use you find for them. From browsing through several dozen MOC folders since leaving the dark ages, I've found that nothing turns me off an MOC quite like a wall made of panels stacked several high and over a dozen long. However, in a single horizontal row of reasonable length, or as a small part of a large structure, panels can blend in well without taking away from the overall appearance, and they would work well as hidden structural support. That's my opinion, anywho.
For me, for now, panels, BURPs, and LURPs are going to be the foundation of whatever I build because I have an abundance of them. I just don't have enough bricks to build walls with or loose cash to purchase more. It's disappointing to know that I won't have the design freedom that comes from brick wall building (as is evident in all those spectacular MOCs), but I'm excited nonetheless to see what can be done with what I have. I'm looking forward to the challenge of creating something interesting with big pieces on a larger scale than storebought sets.
About the raised baseplates, I have three: two greens and one gray from an imperial guard base. I never found a good use for them.