I usually stick around 77–78. Feels like the right pace, keeps me with traffic without pushing too hard. I’ve done 80 plenty, but for longer rides I like it just under that. Smoother, less stress, and still making good time.
That 75–78 range really seems to be the sweet spot for comfort versus miles covered. I find that once I push past 80 for too long, the wind buffeting wears me out way faster.