LOL oh OP, I have a very similar situation however, at this point, how I do it, I play what I feel or what's needed 'right now'. Guild needs a heals? reloggin! Guild needs a tank? same. That's the key, play WITH PEOPLE. Be the hero of your guild, who always has the ability to help. Your wow-life will become rich and full, and have meaning.
Teach noobs in your guild. You're an old hand at this now, there's the achieve of being admired and loved by your guild members, looked up to, and respected.
Have you achieved that yet?