I am also looking to make some raised beds outside and I would like to use wood and make them aesthetically pleasing as well, before we had some very crude beds out of rebar and some old metal roofing while they were effective they didnt look the greatest. Everything I have read says dont use treated wood. Are there any types of wood that is safe short of making it out of logs or finding someone with a mill that can make some for me? I read cedar is ok to use but man is it pricey! Or would it be ok to use treated wood then line the inside with some sort of plastic liner.I dont think anything would seep through it and it would help keep heat in the soil.
I found this amazing site online that has really helped me with creating my raised garden. http://www.no-dig-vegetablegarden.com/ They were chocked full of information. I live out in the bush where not very many things are readily available and I was feeling a bit overwhelmed. This website definately helped calm my nerves, I'm sure it could give you some helpful hints too!