I spent a stupid amount of time with the 2nd boss of Blackrock when I should have just leveled elsewhere, and I spent a lot of time PvPing around the quest turn ins ( I never knew how many alliance my server actually had!!!)

But as far as time spent leveling and not failing on the 2nd boss of Blackrock, it toook about 6 hours on my 5 man team to get to 81. This was questing in Mount Hyjal.

If you quest it will still take longer than a solo toon since you get 1/5th the exp from mob kills, but we all know that already. I would guess when I run my second team that I should be able to get to 81 in 3-4 hours now that I know where to go and what to do.