Tatay and nanay are more commonly used to call one's father or mother. If you want to sound polite to a stranger who looks much older than you then you can also address him/her as tatay/nanay. In a professional setting like work never use tatay or nanay to call someone unless you're really familiar with the person I guess. 

The term "ama" or "ina" is more like honorific form, mostly used in Tagalog region like Bulacan, Cavite, Quezon and Batangas. We also sometimes address grandfather as ama and grandmother as ina instead of "lolo" and "lola".

I'm guessing you are married to a Filipina, then call your in-laws tatay or nanay.

Enjoy learning Tagalog!