Getting those flyers, and the levels needed to use them, is such a big breath of relief! Extra kudos for getting them all mounted up at the same time.

My toons were leveled up in multiple increments. Mage first, then shaman, then rogue. Did pali, lock, and priest together. And just dinged my druid 80 last night. So worst I had to do was 3 at one time. Perhaps a few months from now I work the DK, war, and hunter up (all 60-ish now), giving me an 80 of every class to swap in and out of the party. It gets easier and easier though, as I have more spare cash from extra questing on the 80s to spend on the lowbies (druid still has all of icecrown, peaks, zul'drak, and half of basin left, not counting dailies!).