The amount of experience required for 70th to 80th has been reduced by 20% or so.
That's basically two levels free, in the ten level process.

Some collections open up kills which progress a chain.
You can take a look on wowhead to see if something is worth doing or not.
I would try most collections, even if you only finish them with one or two toons.
And then rotate between toons, so whoever has the least exp on the team is the one with the bonus experience (quest turn in) at the end of the grinding on mobs.

The Grizzly Hills dailies open up at 73rd.
You can do those in 15 minutes or less, with a team.
They're decent experience to 75 or 76; I've done a lot of alchemists via those dailies for that level bracket.

While most of Icecrown has annoying phased areas in it.
You can hit the Shadowvault chain at 77th and be 80th by the time you're done.
Can also do a lot of kill quests or not terribly painful collections in Sholozar Basin.

Also instance a little for supplemental experience.
And do battlegrounds, especially on the weekend for a BG that your faction wins or you enjoy running.