What range should I expect between Bluetooth devices?

Answer

Range can be difficult to quantify as it depends on a number of factors not least the environment it is being used in.

In the first instance it can be useful to use the Bluetooth SIG range estimator at the link below

Understanding Bluetooth Range | Bluetooth® Technology Website

Here you can take data from the Ezurio (formerly Laird Connectivity) module datasheet and estimate the range. Note that the range is dependant on the overall link budget, that is how loud one end of the link shouts (tx power) and how well the other end can listen (rx sensitivity).

The next stage is determining useable range is to use one or more Ezurio development kits to measure the range.

With the final stage being to measure range using the Ezurio on your own PCB. Note that PCB design can have a big impact on range performance and the layout guidelines provided in the module datasheet should be followed to ensure best performance.

Applications using smartphones can be particularly challenging as smartphones are not usually optimised  for maximum range.

The nature of the application/data can also impact usable range. High throughput applications or audio may not get as good a range as low throughput or "bursty" type data.