Most places have free wi-fi to customers, but there are many which are starting to employ time limits so that trolls won't sit all day long and leach off their connection. But if you want to hang out longer than allowed, these time limits can be circumvented. According to security expert Brandon Gregg, you just need to spoof your MAC address.
You just need an app like MAC Makeup so you can spoof a new MAC address and continued Wi-Fi access will be yours. Even changing a single number should do the trick.
An even better trick is use your Wi-Fi to sniff (with an app like Cain & Able, http://www.metageek.net/products/inssider/, NetStumbler) other laptops' Wi-Fi MAC addresses already using the paid coffee shop Wi-Fi. Once you find a few you can copy their mac address as your own. This will give you free Wi-Fi in hotels and other paid Wi-Fi locations.
This, assumes that the paid Wi-Fi locations are owned by the same company and don't require a login.