To be able to load balance you require more than 1 x AP to be visible in any given area and load balancing must be configured on the controller (I would recommend 17dB is the value set on both radios, as that will allow your clients to be load balanced and still obtain top bitrate on most AP's).
Outside of Ruckus config I would recommend that you conduct an RF survey to determine what your coverage is and then progress from there.
You can use the following free software which may help:
http://www.ekahau.com/wifidesign/ekahau-heatmapperNote: I would however recommended in an enterprise environment to get a professional RF survey conducted, but this is entirely up to you.Based on the results of the survey you may find out that there is no floor to floor coverage and you may need to install more AP's.
What you need to look at is the following prior to implementing a Wi-Fi network:
1. Application demand
2. Number of staff and number of devices per staf member (3 devices per person is a common design principle for client devices)
3. Client session concurrency
4. Client bandwidth requirements, based on either application of a nice to have value.
5. WAN capabilities.
Once you have looked at the above you can then design your network to cater for the appropriate number of clients and the bandwidth needed by the clients.
Just remember coverage is nothing without performance, and performance is always influenced by design.
Good Luck