I use [ bitcoins ] at the newsstand by my office building in midtown Manhattan, to buy chewing gum and newspapers. I use them to make charitable donations to a school in Chad and another in Kyrgyzstan. I use them to pay rent on my apartment on the UES. Eventually I should be able to replace most of my uses of fiat with uses of BTC. I will generally shop at Overstock or TigerDirect when possible, avoiding Amazon until they take bitcoin.
That is because the US Government is still lukewarm about bitcoin. AFAIK you cannot legally sell chewing gum in China for bitcoin, and I suppose that a corporate entity cannot take rent in bitcoin. If the US decides that it doesn't like bitcoin after all, you will not be able to do that in the US either.
By the way, are those merchants actually accepting bitcoin, or do they receive dollars through processors like Bitpay?
I have specific knowledge that all of them actually accept bitcoin, with the probable exception of TigerDirect.