Hi E man!
I have to say that I don't know much about juice fasting. (I assume you have a juicer?) But I have heard that fruit juice cleans you out, while vegetables juices build you up. (?) Just passing that on!
The only fasts I know about are The Master Cleanse
(lemonade diet) and it is AMAZING! My energy level was soooooo high. (not really the kind of energy for running or strenuous exercise - although others have said they have energy for that - but the energy I had was that I was just NEVER tired - stayed up late, did my errands around town in half the time, tapped my toes...I was just BUZZING) Anyway, you get the picture. The lemonade fast, I suspect, would give you more energy because unlike the fruit/veg juice fast you're not digesting anything at all (that juice has some pulp and stuff to digest, I think)...so your organs get a rest, get cleansed, get detoxed and YOU get the energy that used to go to digesting your food. woweee.
Also...there are 3-Day Apple Fasts and 4-Day Pear Fasts: //www.curezone.org/forums/m.asp?f=166&i=2
I have done the 3-Day Apple Fast and it reeeeally did detox me, I felt it in my whole body, esp neck and shoulders...
So...you've got quite a few options! Which fast is best for you?
Hope this helps a bit!
I'll include the link for The Master Cleanse
in case you're interested in that too...