Gregg, the reason measuring the decibel level is helpful is it gives you a real world idea of how much power is required to drive your speakers to what you consider "loud". Check your speaker's sensitivity. Mine are 89dB measured at 1 meter and 1 watt of power. Each time you double the power output, the speakers play 3dB louder. So, for my speakers to play at 92dB, I require 2 watts of power. 95dB requires 4 watts, 98 dB requires 8 watts, and so forth. Extrapolating the curve out, I require 32 watts for my speakers to play at 104dB. At 104 dB I can't be in the room for very long. On the other hand, 110 db requires 128 wpc. So, the power requirement increases exponentially versus decibel level. You can do the same for your speakers. Just start with your speaker's sensitivity rating and add 3dB for each doubling of power starting with 1 watt (assuming your speakers are measured 1 watt/ 1 meter...most are).
I mention this because you may find you don't require as much power as you thought. 100wpc may be plenty. 200wpc may add some weight and headroom, but I'll bet you never use it.