True Reincarnation
Editor: This section is going to take some time but a guildie of mine has committed to do this as he goes through a TR himself. This will include strategies, thoughts, best XP grind and more, but it’ll take some time, possibly a month or two. I’d love a table comparing normal XP (capping at 1.9mil XP for instance) and comparing it to someone that’s TRed once or twice.

XP table can be found here:
http://ddowiki.com/page/Experience_points_after_Reincarnation%28s%29?useskin=sparseman
My grind is based on caster (wiz/sorc) with random classed partner or solo.
4.4 mil xp is a lot, but you will have tons of xp to spare. For instance, I never touch (or barely touch) catacombs, 3bc, restless isles, shavarath (and i’ve also not gotten around to mixing in sentinels, carnival, or red fens). Theres really so much low lvl content in this game that you can really skip around a lot on the lower packs in particular.
Another key to making the grind easier is to take advantage of xp storing. You can store up to 1.99 lvls above cap, and it will be a huge benefit to do so, only lvling up once you’ve hit at least 1.8 lvls stocked up.
Here goes a rough quest strategy…
Don’t hop into delera 2 until capping to 8.99 (lvl 7). Take your 8th lvl then grind the hell out of delera 2. You’ll be well over 9 by then assuming you’re going with the 1.99 cap approach. Take 9th lvl and grind out part 3 if you like it and part 4.
Just grind diligently on any mixture of your favorite quests in the middle here (sorrowdusk, threnal, whatever).
If you have a rogue with you, take advantage of the huge amount of xp in shadow knight to prepare you for shadow crypt.
Don’t enter shadow crypt til lvl 12 (You can safely be storing lvl 13 without worry of capping in shadow) and go ahead and grind it on elite before stepping into normal or hard for maximum xp. Do hard, norm, and casual once afterwards to suck up the rest of the xp (15 completions total).
You can dabble around in necro 3 quests (tomb of the blighted in particular is a ~5 minute grind, and could be sped up even more if you are with a good group of friends I suppose by splitting up).
You can mess around in sands, in particular wiz king can be grinded on hard at lvl 14 or elite at lvl 15, based on your comfort lvl with the quest.
GH and necro 4 should follow. The majority of GH is easily grindable, though a couple are just too annoying to bother. POP, Madstone, and Crucible are fun and a huge source of xp if grinded thoroughly. Necro 4′s temple of vol and litany are 2 efficient and rewarding q’s. The other q’s are annoying without a decent partner.
By the time you hit vale you’ll be 17 (hopefully with a lvl stored up) and then its all downhill from there. Grind vale and monastery, prey if necessary, and iq + dreaming dark will top you off easily enough. Shavarath can also be mixed in here if you like those q’s. Doing shrouds, reavers, + any other raids you need some loot from you’ll hit 20 easily enough without the need of a single pot (although obviously it will reduce the grind, which may be necessary for those who are more sane).
Hope this helps for those aspiring to tr for a first or 2nd time, or +. The quest grinding is going to heavily depend on your play style and if you like to party or not.