I have only 1 team at 90 so far, doing heroics and stuff, but have a 5 between 85 and 90.

For ease, the team I'm playing at the moment is pretty damn easy. Tank (I use a Warr, but a Pally is just as good), a Disc Priest and 3 Ele Shaman.
(Ele Shaman still have access to a couple of heals in desperate times, spamming Chain Heals when things get rough is usually sufficient to supplement the Priest)

With decent marco's, you can pretty easily reduce most of what you're doing to like 3 main buttons, with maybe a couple of others for cool downs and "panic" mode.

Any team with more than 1 healer is going to be resilient and fairly easy to play, but personally I'd probably want at least a couple of pure DPS specs in there too.

I have a 5 Monk team, and started with 4 of them as Mistweavers, but switched 2 of them to Windwalker as whilst I was never really dying, DPS was getting kind of slow the higher level I got. With 1 tank, 2 MW and 2 WW I have cleared all current heroic 5 mans, pretty easily in most cases. The ones that weren't "easy" were generally mechanics based, not survivability issues.