#1 is to get them exposed all the way... No matter how big, you can't see all of them if there's any fat on there. I'll tell you from experience, that if you're trying to be big and have a sharp cut sixpack at the same time, it's hard to do. I did it, but it took me 20+ years of farting around with different calorie intake of various mixtures of protein and carbs, and fine-tuning my heavy lifting vs. aerobic workouts. I think the best thing for motivation is to get down to a body fat level where you can see your abs WITH veins ontop, then you know what you're working with. They might already be fine as-is, once you see them fully exposed. The veins popping out are the marker for when the body fat layer is down to the very minimum.
If you are already down below 7 or 8 %, and you want bigger bricks, then definitely more weight/low reps. The only thing is, and I know and respect the opinion of other lifters who will debate me on this, but I think you can also go too heavy and wind up with the whole abdominal wall sticking out if you get the abs too thick. Bottom line is that you have to experiment with your own body and your metabolism, and you will eventually get it the way you want it. If I did at 40+, anybody can.
Charles