I personally have done VERY few collection quests and still easily hit 80 and that was initially without the BoA exp bonus. The rule I used for the collection quests was 1. does it open up a chain of quests, 2. Is it 100% drop rate, if it meets those criteria I did the collection quests and in the case of the chain quest I made sure the chain was at least another 3 - 4 quests.
If you do both sides in Northrend there is more that enough xp once you play fully rested (although with a 5 man team I am not sure how much difference that makes).
My last point would be, get yourself a guide of some sort, whether it is free or a paid one, this way you will know if you are on target level wise, if you are lagging a little ,run a dungeon and it will catch you up fast.
Just my 2 cents