There's not much variation in range of operation and its one of the last things you'd want to consider while choosing a headset. Whats more important is the range that your Bluetooth Version supports. Most headsets are limited to a theoretical range of 33 feet, which is a limitation of Bluetooth technology. So you can go a good 10 to 15 feet before gaps and hiccups start to creep in, though a few headsets can make it to 20 feet and around a wall or two before this happens.
Most home models have a battery-powered headset and an AC-powered transmitter that connects to your audio or video gear. Radio Frequency models can transmit signals through walls and floors, so you don't have to be near your sound system, enabling you to use them in other rooms or even outdoors. But they are also subject to interference from other devices, such as cordless phones and microwave ovens, that operate on the same frequencies (often 900mhz or 2.4ghz). RF technologies include FM (analog) and digital spread spectrum.
Wireless headphones that use infrared technology, much like a TV remote does, require a direct line of sight to the transmitter.