I still plan to do this, although one single color. I'll send the T-shirt company an email today and see what color has the most in stock. My initial inclination is to go with the Premium Heather (basically gray) with Black logo. It's simple, looks nice, and will hopefully make most people happy.
Apologies for not keeping up lately. I was out of town for all of Christmas week, Jan 10-14, Jan 16-21 and last weekend was my best friend's wedding, so it's been a hectic few weeks. I'm back now! I'll get the ball rolling again.