Pretend that you just found out your parents have passed away. What do you wish you would have said before they were gone? Write them a letter and say those things. "Write" the letter (don't type it or email it). They will treasure this.
spend as much quality time with them as you can. It is a comfort to them while they are here, and a comfort to you after they are wrong. You will cherish those memories with you create When those memories are all you have left.
I think parents would like to know that children try to follow their example in life. Let them know that in some difficult situation you asked yourself what they would have done, and then tried to do the same. I think of my parents often, but I doubt they realize this.
I guess it all depends how your parents treated you in the past!... keep in mind there are tons of Males & Females out there that don't have that Paternal/Maternal Instinct, keeping that in mind most children begin by loving their parents; after a time they judge them; rarely, if ever, do they forgive them for something horrible done to them.
In my case My heroes are and will always be my parents. I can't see having anyone else as my heroes.
With me being a father I think My children need my presence more than my presents.
As a parent and grandparent I can tell you what's important to me (and my mom, too).....TELL THEM! You don't have to be mushy about it if that's not your style and never try to be anything that will sound fake to your folks. Something as simple as a phone call just to gossip and giggle, if your family is like mine and you celebrate holidays with a big potluck...do the majority of the food prep, and don't ASK if it's okay (unless you think it would hurt Mom's feelings), SAY you'll be doing yada yada yada. My most precious gifts are the plaster of paris Mother's Day gift my daughter made for me as a little child. Those are the gifts your folks will remember, not the pricey "because it's Christmas/birthday/anniversary" things. Show people how much you respect your folks by being thoughtful, compassionate and generous to others. Nothing will make your folks prouder of you than to see the lessons they taught you being put to use. Just be there for them.
My mom has saved my life; literally, a bagillion times. She's had to do things that made me hate her to keep me safe, and it takes so much to do that, to say 'no' to someone you love especially if it turns them against you. I'll never be able to repay her for that; ever, but I know my time to show her how much I appreciate her is limited, so I just do everything I can to respect her and show love for her and show my loyalty to her even when it's not easy ( i.e. letting go of friends that are disrespectful to her, obeying her if she says no to something even if it's really hard to ). You can give your parents all the gifts in the world, but it's not going to mean anything if you turn around and don't put your money where your mouth is. That's my advice to you; I hope it's helpful :)