When I'm riding in the city I take up a full lane square in the middle. I notice a lot of cars just slowing down behind me hoping I would move over at some time.
No freaking way. I am a vehicle by traffic laws and deserve to take up an entire lane, plus I cruise at 20+mph so it's not like I'm holding everyone back.
I do this on roads with 3 lanes or more usually(most roads I ride on are 3-4 lanes each way so huge). It's very rare for them to honk at me but I hate it when they do that, no way I'm moving except if it's a huge bus or something like that. I usually see them first and signal them to pass and I move to the side; as soon as they pass I go back to my position.