I run breached keep or heart of sin, honestly all those "XP runs" IMHO are stupid.
Not sure if they are "stupid", but they're certainly boring (for me), although technically efficient when done for a good period of time, which would be at least two or three hours. I've tried the "audience runs" (repeating the Royal Audience quest in Act 2) and with 3 other players (usually from my clan) on Torment 6 we would get around 1.75 billion experience in about one hour. I've done that for about two hours and got bored of it really fast.
I'll soon get Paragon 280, I'll try to get to 300 before the experience bonus ends, might be tough to do for me since I prefer to just "farm normally" and luring mobs them together, not just avoiding them to hunt for elite packs only (honestly I hate it when people do that in public games). I can understand skipping maybe three or four mobs roaming around, but if I can see about 10+ mobs grouped near another pack of 10+ mobs I'll definitely run around gathering them in the same spot and proceed with the killing. I do that mostly in Act 1's Weeping Hollow (nice density there, most of the time anyway), Act 2's Desolate Sands (and various crypts, especially Vault of Assassins which can have up to around 7 or maybe 8 elite packs, maybe even more) and Act 3's Keeps.
I can play comfortably enough (and kill fast enough) in Torment 4 with my Barb, but I wish that the monster density would be higher without necessarily adding up to the difficulty as a price (I.E. not having to move to Torment 5 or 6 if I want more density, staying in T4 but increasing the monster numbers, period). All of this bonus experience will spoil me, it's been like this since the patch came out and I'm getting used to get at least 3 or 4 Paragon levels almost every day, after that when they remove the bonus it'll feel very slow, oh well.