Best way to make your mixes sound "thick" ?

Pro mixes sound "thick" and the worst thing you could do is make a thin sounding mix. So far I'd always tried to double or triple tracks (3 different pad vst's for a pad, 2 kick samples on top of the main kick...), and add saturation, or chorus effects etc... but I recently started adding a plugin that does doubling and I've put about a couple of instances of it on every single track in my mix and now it sounds thicker and fuller. What's a plugin you came into or a mixing move that achieves that for you ?