In every cases, the best alternative is always P2P transactions. The issue is that hardly ever you are going to find someone willing to negotiate. Maybe if there was a shop where P2P traders could meet would be a nice idea to be introduced in a cosmopolitan city like NY.
P2P transactions are good in countries that ban Bitcoin or consider Bitcoin illegal, so people resort to such methods. However, in countries that do not ban Bitcoin and have exchange services, P2P is not necessary.
As for your statement, “If there was a store where P2P traders could meet, it would be a good idea,” I think that this is not a good idea at all, because all P2P transactions depend on maintaining privacy and take place anonymously, far from the eyes of the government, so it is not appropriate for them at all to meet in a known place.
For me it's not a problem to reveal my identity when dealing with BTC. I just would like to sell and buy for the current fair market's prices, but through exchanges it's impossible, because there are always spread or order's fees, besides the abusive withdrawal fees many exchanges charge, going beyond costs the blockchain demands.
I consider P2P transactions to be important even in countries where Bitcoin isn't banned due to the reason presented above. It's annoying to become an "hostage" of exchanges, what means that if you want to deal with BTC, you have to do this through their services or you can't adopt the digital currency at all.
ATMs could be a great alternative, if fees weren't abusive as well...