I bought some of the pre-seasoned Lodge on
Amazon and love them. I'm tough on them, but they're easy to get back to normal if they rust. I use my 8" one the most and I have a ceramic cooktop. You just can't slide the pan around or bang it down. It actually heats better than my other pans since the iron is more even and holds heat better. It's great for searing meats, but I use it for everything.
Even if you buy pre-seasoned, I still recommend doing an initial cure and then once a year. Alton Brown recommends doing it on New Year's Day and it does help me remember!
To clean, I will wash it with water and a scraper. If I need to, I have also cleaned it warm with a little oil and some kosher salt.
Here are cure instructions from I'm Just Here for the Food:
Heat the oven to 350 put the cast iron on the top rack of the oven and a sheet pan or foil underneath on the second rack.
When the pan is warm but still touchable, take it out and put in a dollop of solid vegetable shortening (plain Crisco). As it melts, spread it around with a paper towel so there aren't any pools of oil.
Put the pan back in the oven upside down and bake for 1 hour. Turn off the heat and let the pan cool for a while before removing. Wipe the pan clean, but don't wash until after you use it.