The single target rotation when tanking without a PLD cotank (solo tanking or with a WAR cotank) is BB>SE>SP. The single target rotation when tanking with a PLD cotank (or a WAR cotank that doesn't know how to play OT) is BB>BB>SP. The without rotation is different from the with rotation because, while it generates less enmity, it has higher damage dealt and, with the 2.1 enmity changes, you should never need more than that unless you're running with another tank who feels like riding your ass. The OT rotation is SE>SP (maintain both debuffs with 100% uptime).
For AoE situations, it depends upon what my current Wrath situation is. If I've got 5 Wrath and Infuriate up, I'll throw out a Steel Cyclone>Infuriate>Steel Cyclone and just start the ST rotation while cycling through targets. If I've got 5 Wrath but no Infuriate, I'll throw out Steel Cyclone>Overpower>Overpower and then start the ST rotation while cycling through targets. If I've got Infuriate but no Wrath, Infuriate>Steel Cyclone>Overpower>Overpower and then into ST rotation cycling targets. If I've got no Wrath and no Infuriate, I'll throw out 4-5 Overpowers before going into ST rotation while cycling through targets.
The main reason that I use Steel Cyclone instead of simply Overpower spamming with Unchained is because of the TP cost. Steel Cyclone generates a metric crapload of enmity in a single application (not sure how big the enmity modifier on it is, but it feels like 5x or so since an SC>Infur>SC combo at the start has let me completely ignore a target for the entire fight and still keep aggro) and is basically free; Overpower generates more AoE enmity per second than Steel Cyclone w/ ST rotation, but it costs a shitton. If you use Overpower spam for AoE instead of Steel Cyclone, you can expect to have to just stand around at regular intervals recovering TP. Steel Cyclone lets you forgo that and just keep doing ST (which means generating Wrath stacks for future IB usage) because it generates *enough* AoE enmity.