It's been a longstanding debate in Daily Digest over whether there is enough merit playing two colors and being less powerful or going with three or more colors and being less consistent. Well, with how poorly control performed at Pro Tour Khans of Tarkir, perhaps sticking to two colors isn't the best choice.
Sultai Control was a thing during Theros Block Constructed, and some thought it would make a splash into Standard, but that was before they saw how insane Khans was. As it turns out, there's a lot of powerful stuff in Khans that might fit into control decks if you want to get a little creative with your control decks.
This deck splashes a fourth color for Abzan Charm, Banishing Light, Last Breath, and the all-powerful Siege Rhino. At the very top end, there's a pair of Sagu Maulers to provide an untouchable win condition. If those aren't good enough, there are also some Elspeths in the sideboard.
I like this list a lot although I'm not sure if this is actually the best build. It does show what's capable if you're playing Sylvan Caryatid and are willing to play some trilands.