For my current team, I brought them into Northrend at 68.
From 68-70.3ish, I did most of the quests in Howling Fjord (~100 or so), and then I farmed Utgarde Pinnacle's Prince Kelesith for his blade about 5-6 times. That brought me up to level 71.
From 71 to 73 I went to Borean Tundra, and completed about 105 quests there (also did the Nexus shoulder quest, but no other quests in the Nexus)
73 - 74 was spent in Dragonblight. I've done all but 3-4 of the quests for the achievement there.
74-75 was spent in the Grizzly Hills. I then took a break and started working on buying gear and resting my characters
75-78.2 was spent largely on dailies and instance grinding (with rest experience, you should be able to get at least 230,000 exp/hr in an instance - which is about 1 level every 6-7 hours)
78.2-80 is being spent in Zul'Drak, there's enough quests here (+Gundrak instance quests) to ding 80 at this point.
That leaves me with Sholazar Basin, The Storm Peaks, and Icecrown citadel untouched @ 80.
On my Horde team, I started them at Northrend at 70.
I finished Howling Fjord, Borean Tundra (3-5 quests away from the achievement), Dragonblight, Grizzly Hills (10-15 quests from the achievement), Zul'Drak, and about 15 quests in Sholazar Basin before I ding'd 80.
------------------
If you dread questing, you shouldn't have a problem instance grinding, but ONLY instance grind if you have rest experience (otherwise, questing is much faster). Also, if you dread questing and instance grinding, then simply get to 73 and do Grizzly Hills dailies until 80. It would take about 52 days to get to 80 with only 1 hour of game play per day. (73-80). That's only a bit over a month of casual play, plus you'd clear about 13,000 gold between now and then just doing dailies, and you'd have all of the quests in Northrend available in case you ever decided to do the quests.
Cheers
Connect With Us