I am not a huge fan of plastic in general and I don't really like it around food. So last summer, I purchased a couple of LunchBots Stainless Steel Containers for our picnic lunches.
(Image from LunchBots)
I am a pretty big fan of these. They have worked perfectly for our picnic lunches in the park and have held up beautifully since last year. We have the LunchBot Duo Orange (the one in the picture) and the Eco Green, the larger one. If I had unlimited money, I would buy lots more of these, and even without unlimited money, I will likely buy another one soon. I am wanting one of the Quads, since the four little compartments would be perfect for packing my kid's food in, since she likes little dabs of lots of different things.
If you do buy one of these, pay close attention to the sizing when you are deciding. The main complaint I saw in reviews was that they were smaller than people were expecting, so I was careful to look at that when I was ordering. I would also mention that the entire container is made of stainless steel, since for some reason, I assumed that the lids were plastic when I saw the bright colors and I was surprised when mine arrived.