I don't have a long head, but have a giant noggin. If you're looking for more city style helmets, you might look at the XXL Bern brentwood or the L/XL Nutcase. Both work pretty well for me. I also had the Giro Rift that was fine and there's a Trek helmet that fits ok. The Bern has the best fit for me. I find I prefer the more closed style helmets for the riding I do (utility cycling sometimes in the rain etc...) The Bern has the most innocuous look on my head, the Nutcase looks like a giant mushroom. If you're looking at Bern the Brentwood is the only one that comes in XXL. I would have preferred a Watts but giant noggin strikes again.

+1 to trying a bunch on. What fits for you won't necessarily work for someone else. I hate the Bell helmets and find the shape to be all wrong as are Specialized helmets, they work very well for my brother. Once you find a brand that fits pretty well, look at the different models they make.