I typically use my credit cards to buy things between $10-$25. I never go beyond that.
The biggest debt I have ever had to pay back was for my EMT classes (around $1,000 in loans, not including fees that I paid with money I saved up). I don't like going beyond that. Unless I can get a good deal to pay something off with my good credit, I only use the cards to pad my credit score with low-cost purchases.
I know people who've used their cards to pay off $200 in bills. FUCK that.