My personal preference would be north/south. It's the way my bed is situated, and i've got 4 trellises. Everything's working great. Here's a small section of it.

Mine are north south too! EG you do not have any shading problems?

nope no shade at all, only shade we get in the back is around 5 pm once the sun goes over the orange tree and that's only a small % of the garden

Does anyone think the SIZE of the bed matters when having North/South or East/West beds? would having smaller beds but more of them be better? and make the whole orientation thing a moot point>

I got to thinking, that I may have told you wrong....let me clarify my orientation better. My bed is 4 ft wide by 25 ft long. The ends that are 4 ft are located on the north and south ends of the garden. There- that is better.
Socalgirl - when I designed this bed, I was somewhat concerned that the growth on the 4 trellises would shade the other stuff. In fact, it actually surprised me - as it actually does not, because of the way that the sun tracks across the sky. The only problem that arised was, out of 20 okra plants- about 6 of them in a corner are a little shorter than the rest of them. That's it. I'm so relieved....As you know, I put alot of photos of it on here, and after this weekend- i'll try to get a shot of the entire thing, so you can see how everything is doing.
Di-h, I think that the way mine is situated, it could have been 50 ft long, and would have made no difference.

Ok I spent some time in photoshop quickly "planning" out the beds. I'm gonna post the pic tomorrow and see what everyone thinks.

Guess I'm backwards from everyone else, but my beds run east-west (long side runs east-west). I have 9 beds now, mostly 4x8, in what will eventually be a 3x4 arrangement, and wanted to be able to trellis any of them and have the trellises shade the path/aisle behind each bed without shading any growing squares. I've got some pictures on my blog. Right now the only trellises are on the northern most side of the north beds, but with crop rotations they will move up to the next row next year (or that's the plan).

Here is a link that might be useful: my blog - David's Folly

I think it mostly matters which way you're going to orient your trellis or tall plants. The taller stuff should generally be on the North side, so that it doesn't shade the other things. So if you have a short trellis, along the short side of your bed, then that end of your bed should face North. If you want a LONG trellis, along the long side of your bed, then the long sides should face north/south. So either way can be correct. And probably everyone here is right. :) Make sense?

makes sense to me.
As I've got the beds laid out inground pretty much like plan D I am noticing they are too long, and I like the walkway across the middle. So plan A might be better.
Eeek its all so complicated!