For most furniture paint projects these days, I use Polycrylic (affiliate link) as my top coat. It gives me the durable finish I want, but doesn't yellow over time like Polyurethane will. 10 Paint Tips & Tricks You Never Knew!
I like the idea for kitchen counter. (AW) DIY wood plank kitchen table picture step by step ~ would also be really really awesome for kitchen counters! Stained black with high gloss protectant over them.