re: How to

What Bent wrote on a TS. Plus his has the advantage you can use a single straight blade, and don't have to dick around setting up a Dado stack. Zip 1 1/2" then play it down and zip 3/8". I would think the cuts would be cleaner than with a Dado too.

Of late, if I have to do a 2 pass cut to make the width, as in a 1 1/2" dado/rabbet, instead of the TS and a Dado blade. I'll use a router table, and just over 1/2 the width on the bit. So I'd look for a flat bottom cutting 1" bit, and move it over enough to cover the 1 1/2" in 2 passes. 

For speed what Bent wrote is the boss. I think for accuracy the router will deliver, kinda depends on what ya are looking for as an end result.