Groovemeister, did you choose yet?
I have a few suggestions. Not to be totally depressing, but I'm female and my mum recently died (February). All those things that I'd wanted to do for her or with her, they are forever gone. I never had the time. I never had the money. It wasn't something she'd like. Blah blah blah.
I wanted to get her REAL lead crystals for the dining room chandelier, it only had a few and it wouldn't have cost THAT much, but I didn't. I wanted to take her for a drive up to the lovely autumnal foliage and beyond because she really seemed to like those nickel slot machines. Hah! Just a girl trip. Me and my mum. Something she might enjoy.
Time is the most precious thing you can give.
So here is my suggestion, even if it costs you a bit, and you have to take out a loan to do it. Or start saving, in earnest for it, now. Tell dad you have something really special planned for him later this year or next year.
LEARN FISHING. LEARN ALE. Take lessons, if you have to, so you can chat about fishing stuff. Bring along a sampling of ale. Plan a weekend away for the two of you, where you can wander off drunkenly and pee on things and not have to drive.
Something that really connects with your dad. Something your dad will talk about. As in "MY son took me to the ultimate fishing place and we fished and drank and peed and puked in the bushes." Or whatever guys do.
Man stuff.
You don't have to do it every year. He might do the same the next year, and you will have the proper training in ale and fishing and puking by then. Yes, I'm being silly, but CONNECT with your dad while he's around.
I found a mother's day card that I never gave my mum. I put it off last year. And by the time mother's day rolled around this year, she was dead. I last saw her in October when she could easily out-walk me at 70+ years old with cancer. I just have a bad back. Next I saw her in January, and she was bed ridden. All the simple things we would do and enjoy, like crossword puzzles, she was no longer able to do.
A friend of mine and her sister went in on a day at a fancy spa for their mum. Their mum would appreciate it, and they knew it. You know what your dad would like. And what parents seem to want to know is that their kids are okay. Will be okay. And perhaps share in some of their interests, or make an effort. How many interests did you have as a child that your parents were interested in, ONLY because YOU were interested in them? Probably a lot.
Do the same for your dad. If you can. When you can. As soon as you can. Because if you wait, you may end up staring at a blank card for a dead mother on mother's day.
You have exactly the time you have...while talking or being around them. Nothing more is guaranteed.
How about a hot air balloon ride? Something neither of you has done before. That you could both talk about.