Nearfield is indeed 2 to 6 feet. It is an important consideration in many designs as most two-way speakers run a 6 inch woofer up to 3 or 4KHZ. This makes them ONLY suitable for nearfield because already above 1KHz the woofer is starting to beam (i.e. changing from a floodlight dispersion pattern to a spot dispersion pattern). When you sit in the far field it is very important to have a speaker with even dispersion as the room reflections play a much bigger role in what your hear from the mid range and a "spot" presentation will not sound natural at all.
Very few nearfield designs have wide dispersion - you can check this very easily by looking at the X-over frequency. Any design with a X-over at 2 KHz or below (between mid/bass and tweeter) will ensure wide even dispersion.
More farfield designs have wide even dispersion but again you may want to check the X-over frequencies to be sure. (For example B&W make many farfield three way designs with a tweeter X-Over close to 4 KHz and this design will require careful messing around with toe-in/out to get the right mid range balance at the listener and even then the sweetspot on these designs is ALWAYS narrow because of the way upper mid range behaves like a spot light. A good flood light B&W design was their Silver Signature)
Very few nearfield designs have wide dispersion - you can check this very easily by looking at the X-over frequency. Any design with a X-over at 2 KHz or below (between mid/bass and tweeter) will ensure wide even dispersion.
More farfield designs have wide even dispersion but again you may want to check the X-over frequencies to be sure. (For example B&W make many farfield three way designs with a tweeter X-Over close to 4 KHz and this design will require careful messing around with toe-in/out to get the right mid range balance at the listener and even then the sweetspot on these designs is ALWAYS narrow because of the way upper mid range behaves like a spot light. A good flood light B&W design was their Silver Signature)