Last year, we planted the majority of our tomatoes in box # 1, but this year, they are growing in box # 3. I think they can succumb to certain diseases if in the same spot year after year. We'll see how this box does.
We are growing about ten Tula tomatoes and five cherry/grape tomatoes in one box. They're planted on opposite side of the box with herbs and mints in between.
So far, they seem to be weathering OK, considering the chilly weather and many, many rainy days we've had.
As you can see, the tomatoes are still very little. We planted the seeds in one of those seed-starter kits you buy at Lowe's or Home Depot. When the seedlings were ready, we planted them in the box. We lost several to cutworms, and the straw method seems to work... We haven't seen any cutworms since.
I bought our seeds from Seed Savers Exchange: http://www.seedsavers.org/Details.aspx?itemNo=251