I am not sure which would be faster overall, but I would think doing at least the island dailies then running instances as you can would be very beneficial.

However, I personally am not worried about getting epic flyers for all my toons just yet. Being that we cannot use flight of any kind in Northrend until what 77 or 78 I think. I would rather stockpile the money for the 2 main sinks in WOTLK the no cooldown teleport ring and the 3 seater caravan with vendors attached.

Not to mention the monies it will take to level all of my friggin professions to max again. lol