I always set up in a U shape so people can walk in. I have too much stuff to display on one table across the front of the space. I DO, however, have the table across the back of my space as close as possible to the "aisle" (leaving room for my display pieces on either side. This accomplishes two goals: !. It gets my items closer to people and they don't feel that they have to walk "too far" into my display to look at stuff up close. 2. It gives us a place to sit behind our displays and still be protected from sun and rain.
I also set up this way for indoor shows. I'm a hands-off seller, in that I am not in my customer's faces. It's easy to see where we are at all times and if someone makes eye contact with me I say hi, good morning, or whatever. That's it. I watch (in a very not noticeable way) to see if anyone looks like they want help or is ready to buy something but for the most part, I let them alone. They know where I am if they have a question. I would NEVER park myself in front of my display, ever. I've been to many craft shows as a customer, and I steer clear of those booths whose crafter/artist is standing in the middle of their booth or is looking like they're going to follow me around their booth, telling me about their items. I HATE that. . . . most shoppers do. Nothing, I repeat, nothing makes me leave a booth faster than to be instantly "assaulted" by the crafter who feels she/he needs to tell you everything about their items before you've even had a chance to look at them.
Sorry, seem to have rambled myself right off the subject, but my setup both encompasses my needs as well as what I believe will work best for the customers.