With current versions of ArubaOS, all SNMP erlated topics are covered in the ArubaOS SNMP MIB Guide.
The MIB files themselves are the best reference.
In additon, the Aruba Instant units offer good SNMP MIB support as well.
Most of the AP-specific stats are indexed by radio, and or BSSID as well as AP. Since most of this data
is relevant to a radio, a channel, or an SSID, the numbers are not simply indexed by physical AP units.
To give just a start on what is possible:
Dealing strictly with an ArubaOS controller, I'd reference the wlsxWlanAccessPointInfoGroup, and investigate down the MIB tree:
.1.3.6.1.4.1.14823.2.2.1.5.2.1
wlanAPNumBootstraps
.1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.20
wlanAPRadioNumAssociatedClients (indexed by AP and radio)
.1.3.6.1.4.1.14823.2.2.1.5.2.1.5.1.7
wlanAPBssidNumAssociatedStations (indexed by AP and BSSID)
.1.3.6.1.4.1.14823.2.2.1.5.2.1.7.1.12
These MIBs are indexed per BSSID
wlanAPNumClients
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.2
wlanAPTxPkts
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.3
wlanAPRxPkts
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.5
wlanAPFrameRetryRate
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.10
wlanAPFrameRetryErrorRate
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.15
wlanAPFrameRetryErrorRate
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.16
wlanAPFrameRetryErrorRate
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.17
wlanAPFrameRetryErrorRate
.1.3.6.1.4.1.14823.2.2.1.5.3.1.1.1.27
etc...
wlsxWlanStatsGroup.wlsxWlanAccessPointStatsGroup.wlsxWlanAPRadioStatsTable (indexed by AP and RADIO)
.1.3.6.1.4.1.14823.2.2.1.5.3.1.9
It really depends on how we want to see the data, and how many graphs one wants to create in tools such as MRTG.
It goes without saying - the advantage offered by Airwave is that most of this work has been simplified, and is readily available in various forms.
I hope this is helpful.