In Eclipse, this is easy to do. Use the Android Virtual Device Manager (AVD) to configure as many emulators as you want. Depending on whether you upgraded to the latest version of the Eclipse plug-in, the start button for the AVD manager will either be a black phone or an Android Robot puzzle over a black square with an arrow in it. In any case, this is on the toolbar next to shortcuts for saving, printing, etc.
In AVD, you can create different emulators with different versions of Android (load other SDKs in the "Available Packages" menu on the left). After creating emulators, launch them using the button on the right. You can use several emulators at the same time if you want. The emulators have a program already installed, called the "Custom Locale", which allows you to change the location information. You cannot do this when creating emulators, but it persists when you do in the emulator, so you do not need to do this every time.
After that, to select which emulator your program will work on, change its launch configuration to manual. This is done by clicking on the additional arrows next to the green "Run the program" button, selecting "Run configuration", the "Target" tab, then select the manual mode. You can also do this by right-clicking on your project in the project browser (list on the left), and the parameter is located in the "Run As" ā "Run Configurations" section.