If you get boosted 1-60 (60.9 on one char) will be 8-10hrs. 70-80 with a dual box won't be too awful, can follow the quest guide (probably faster with 2 accounts) or get boosted. Should take roughly 25-35hrs, you can afford to skip a lot of collection quests since they changed the xp curve. 70-80 is probably 50-60hrs depending - lots of collection quests you can't afford to avoid but with only 2 it won't be too bad.

That leaves you with 4-5 days /played without rested at the very fastest. More typical times would be 6-9 days.