Ravi,
Chistopher is totally right, you should do site survey, it can be predictive one as well, but should be done after intense investigation of your environment and your goals. Project would also depend on the goal, you might want to have high throughput or high range, but I would not recommend to put APs at 20-26 dBm of transmitted power for sure - this will most likely result in worse channel performance as with such power, tens or sometimes hundreds of meters (in open area it can be even couple of kilometers if you care just about free space path loss) are not enough to get rid of co-channel interference, what is a painful factor especially with 2.4GHz where you have small amount of channels for your channel re-use plan. Especially, when we are talking about a long range of signal that is not useful because it is below your devices sensitivity (like -65 dBm for many voice devices) and above SNR ratio that would make other APs ignore the signal and not get 'distracted' (this threshold is way lower than -65 dBm).
You will be amused by the way WiNG operates and by its overwhelming amount of security and troubleshooting features. In theory, all the APs on the market have more-less the same range under the same conditions, as it's just about Tx power. Another factor is the internal/external antenna radiation pattern and how you place it (it can be initially simulated). By the way, if you have a warehouse with high storage racks, you might find it useful to utilize APs with external antennas that would radiate well along aisles and get contained between racks.
Kind regards,
Tomasz
