Thanks so much for the response Doc! The process for choosing new loudspeakers is a veritable minefield. Your reply will help to more easily mine detect those infernal mines.
I'd previously read that 3-ways are difficult/expensive to design. You've confirmed that for me.
I'm not sure I could read a waterfall plot. Nor, could I look at an impedance curve and gain any insight, other than to get an idea of the power demand of the speaker.
I agree on the bookshelves. In fact, with the availability of good DIY subwoofer designs, one could probably get better results than with towers. Besides, very few tower designs can claim to be "full range" with any degree of legitimacy. And, those that can, are usually quite costly. If I had my time back, there would be no tower speakers in my house.
The thought of building a set of bookshelves is very appealing. It's certainly more complicated than building a subwoofer though.
Thanks again for the input!