I think Brayflox because you have a tank stance in there and can shine in mass pulls, so it's the first legitimate place a new tank can practice... but you're also right in that there's nothing at the start that says that, and it relies upon the (new) individual to be aware of the possibilities. I suppose if there's a confident sprout someone who's tanked before there and has the knowledge, or there's a Vet Wot Knows Stuff, they can let the new tank know they can have some more fun..? The mid section is great for figuring patrols, but it's possible to keep reeling stuff in if the team's happy for it. I've had a tank collect the lot up in a nice bunch and have me bard LB it. It certainly wasn't what I'd been used to in there, but it was really effective. That tank was not new in the slightest, however. Van_Arn can probably elaborate if they so wish.
As for mass pulls, someone brought up Castrum Meridianum for that. When I first started running it regularly (as part of the Roulette That Shall Not Be Named), it seemed to be standard practice. Doing bard for it, or Summoner, I quite enjoyed lots of stuff going on. EDIT: Forgot to say, when doing this roulette again of late for moogle tomes, there's been some really choppy, slower pulls and... eh. It felt off after being used to mass pullage there. I honestly don't care either way because I'm in a place where I want to adapt to what the party wants, but it is glorious when the tank(s) are confident enough to just drag the whole lot at the start down to the first boss area. I'm a bard and I like to DoT'n'Run! Don't recall how it was 50-60, but it seems the norm post-60.
I don't actually have a pony in the race, though, and as DPS will mostly let the tank and healer figure it out. I don't require speed runs at all, but at this point I'll just go with it if they want to do that. I'd only say something if they needed further input. I couldn't tank it myself like that, but there again, I don't bother other people with my tanking (it's the best for everyone involved).
That said, I'd love to know what the One Button tanks press is. I'm pressing more than one button when I do it, so am I doing it wrong? What is the button I'm supposed to press on WAR, say? I'm not being sarcastic, I really want to know!