I have a pally and 4 elemental shaman, and I went aldor on the pally and one shammy (the one I'll respec resto later), and scryer on the 3 elemental shaman that won't respec. If I have to go to the Aldor/Scryer tier, I just leave them in flight above the tier if they're not friendly with that faction. Some quests are harder to organize, like the Shadowmoon quests from the Aldor/Scryer camps.. but don't let that stop you from picking the best faction for your character. Look at the recipes you want and the professions you have.