It's not a personal choice that I make to do, but there are many others who do. If you're up in NCC then it seems it's a bit more frequent to get hassled. Around Kent and Sussex it's a little less likely. Most businesses don't really pay much mind, and the worst they can do is ask you to leave. The truth of the matter is, a decently dressed man or woman with a holstered sidearm on their side really doesn't draw near as much attention as you would think. I know I've personally seen a couple of people in the past and not really paid much mind. If you want more info there is a forum for the OC crowd,
www.deloc.org.
As for places it's allowed/not allowed, basically anywhere you can concealed carry, you can open carry as well. The exception being the City of Dover which requires a CCDW permit even to OC. There's also something about parks in NCC that may or may not hold ground, but I don't remember the specifics...