Digital BW, The Print

I'm new to this forum and new to digital B&W. Having just hung up the 
print tongs and bought a digital camera, I'm in the information 
gathering stage for printing. It looks like a lot of people here have 
a huge amount of information on printing with their own printers. But 
I'm wondering if any here also use commercial printers for their B&W 
and particularly for large prints of 16x20 or larger.? If so, can you 
offer any information that you've found to be particularly useful, 
e.g., personal preferences, books, web sites, & commercial printers. 
Any links and all information is much appreciated. Thanks in advance.