Thanks again to everyone. After much thought, I decided that white speakers to replace the white ones there now were the way I wanted to go. So, I spent $85 on a set of 6.5" Clarion component speakers (CM1635's). I was trying to stay on budget, get an upgrade, and also keep in mind that a boat is not like a car where you really capture/hear all of the sound produced by top of the line equipment.
So, I picked up a 4 channel amp (75 watt RMS per channel), a Clarion 10" sub, and this set of Clarion 6.5" speakers to replace only the cockpit speakers. I'm going to leave the bow speakers unamplified for now, as it seems that people just complain about them being too loud most of the time anyway. Hopefully this will significantly improve the sound quality in the cockpit, especially while cruising, without costing too much money.
I'll post up some pics of the install and all of that. I know how much we like our pics here.

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Paul
2007 Four Winns Horizon 220Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)