I use PRTG for my trending, reporting and alerting. I gather number of clients per SSID, # of clients per AP, as well as System uptime, CPU & memory for all AP's and ZD's.
PRTG also makes it easy to build reports. The reports are nothing special.. just the numbers and times.... nothing fancy.
I'm happy with the solution. The only complaint I have is the AP's (sometimes) when rebooted or replaced join with a unique ID (ex. one AP name is - "APA-1"; SNMP shows it as - "ÀŠÞ#Z") that is hard to determine which AP is which. I think I've since found an easy way to do it.
We use PRTG as well and continue to have the issue with the names/MACs getting converted to weird characters when polling from PRTG. How were you able to overcome that? I appears that PRTG is interpreting the character set incorrectly as if you do a non-PRTG SNMP tester the data renders correctly.