My company does a lot of trade shows, so when I started doing shows I asked my friend in the marketing department how I should setup my booth. She told me to put the longest table closest to the customer so that they see the most product at once just walking by.
[from my marketing friend's perspective] The problem with the L shape inwards is that customers walking from the (left in my diagram) are only seeing product on the 30" of the end of the table, customers coming from the right are only looking at the first two feet or so of that table. Most browsing customers will not look inside a booth. (My opinion: soap is often an impulse buy. Most purchases were not planned, it's easy to impulse buy because it's a few dollars.)
The same problem with a U shape, people only look at the table ends, but there it is complicated by the U shape, so coming from either direction people are not looking the two feet further because the table on the other side is blocking their view.
[Marketing friend says] If you have to setup with either inwards L or U, make sure you have your most interesting/best selling items on the end. If it's appealing, people will stop and come inwards. Typically browsing people will not come into a booth.
That said, I do a 6ft and a 4ft table with the 4ft table in front (the 6ft table is set so that it adds another 30" to the length of the 4ft table, so I have 6-1/2 ft facing my customers). I think you would be able to do that with 2 6ft tables as well. The benefit of the outwards L is that I have room inside of it and can help my customers from any spot, without having to walk around other customers. I can also better keep an eye on those rogue kids and other customers if I'm working with someone else.
ETA: Oh, I should also add for the inwards L and U setup, to turn the product on the table ends towards the customer walking by, not inwards to the customer who has come in.
