How Do I Get Ready for an Ultra?

I feel stalled.  I'm sure it has something to do with training setbacks from Grandma's Marathon, but I'm a bit tired of talking about it.  The drive to run and compete has winnowed down to a smolder rather than the fire I had earlier this year.  If you've been following this blog or my DailyMile training, you would know that I had my eyes set on ultras and and that the triathlon holds little appeal to me for some reason.  Developing overall strength and versatility, not to mention a stronger upper-body is a nice outcome of CrossFit and CrossFit Endurance, but none of it seems to bring the much needed oxygen to the fire.  What is it that I need right now to get me moving again, rather than haphazardly trekking out for a run here and there?

I need a goal, an outcome, something to reach for, something attainable yet challenging.  It's not enough to work-out, rather it needs to have meaning.  I really want ultras, but I know my body isn't ready for it now or even the near future.  My current comfortable distance for my knee and hip is seven to eight miles, the distance it all fell apart this June.  That's one-seventh the distance of a 50 miler, which is obviously not going to happen any time soon.  I think that is what my problem is.  I can't see far enough out to say when it's going to happen.

Is one year enough?  50 weeks of training between now and the Superior 50 miler next year, less than that for the Northface Endurance Challenge.  Surely, two years would be more than enough, but too far to keep me driven?  How do I put together a plan I know will work, that will keep me motivated and pointed in the right direction, while maintaining injury free performance?

I'm trying to look back at how I trained for my first half and my first marathon, what mistakes I made, and places I could improve.  I've read prolifically on training, and I've got a relatively good idea about how to go about it.  With that in mind, I'm going to try to rough out a plan to move forward.  The key principles I'm going to apply are:

1. 5-6 days of training.  At least one planned day off per week.
2. Alternating hard and easy days
3. 3 week cycles of increasing distance, 20% in week 1 and maintain for 2 (Lydiard)
4. Plan my peak performance and health for my goal race
5. Develop my distance in stages (5-8k, 10k-Half, Marathon-Ultra)
6. Cross-train like banshee (swimming, Crossfit, whathaveyou)
7. Set realistic, yet challenging goals at each stage
8. Be patient with setbacks and generous with recovery
9. Finally, don't overdo it!

What I need right now is a 5k or an 8k race to suss out my current fitness level, my current pace.  Any suggestions?