Yup, flats are easiest to wash. If I was going to do flats all the time, I would just fold them into a rectangle, and lay them in a PUL cover, rather than messing with all the folding.
You will get your PUL covers poopy a lot when they have liquid BF poop, though, if the diapers are just folded into a rectangle (ie about the same shape as "trifolding" a prefold). To me that is no big deal, but it would bug some people.
Suzan, mama to DS 9-18-07 and #2 EDD 3/4/10 GIRL!.