There are a ton of thin cases out there for iPhones. If you're considering cases from Peel, Totallee, among others, stick with Caudabe's Veil XT. This is by far the most durable and most reasonably-priced option. It fits perfectly, is minimally branded, and feels a lot more grippy than the other two brands. This case is great for day to day use, you won't regret it.
Here's a tip - once you've cleaned your phone and have fitted the case, leave it on; don't take it off unless you absolutely need to. Cases like these are built to be fit on once and left on. Taking it on and off repeatedly will loosen the fit and render the case pointless and susciptible to falling apart.