all my relatives in the philippines do. and believe it or not my relatives who are in the states still do. my cousins in illinois and california, even though they were born and raised there, were taught by their parents to say "po" and "opo" and to "mano" when talking to and greeting their grandparents. when they come for vacations in the philippines they have no hesitation doing the "mano" even to their aunts and uncles. sa US di na sila nagmamano sa mga aunts and uncles but they do to their grandparents. guess it all depends on the parents.
ako naman, pag mga aunts and uncles na naging kabiruan ko na i make the sign of the cross, like a priest giving a blessing complete with "God bless you" ehehehehe! my mom sometimes admonish me when i do so but i always have one defense - "e kung bigla tumanda yan kasalanan ko pa". exception lang yung mga aunts and uncles na matanda naman na talaga, mano pa din. with my uncles with whom i am very close i address them with their nicknames, like "kalbo" or "bentot". pero sa mga lola at lolo nagmamano pa din ako.
kay erpats and ermats, nagmamano pa din ako. but i don't use "po" and "opo" anymore as they told me to drop it and address them as equals since when i graduated from college. sabi ng tatay ko "graduate ka na, pwede mo na ako kausapin ng patas". ganun din mga cousins ko, when they finished college they were told by their parents to drop the "po" and "opo" and address their elders as equals.