Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. First your game file, which is by default in Documents\My Games\Sid Meier's Civilization 5. Then, with a text editor, edit the "config.ini" file in the game directory. Change the DebugPanel = 0 line to DebugPanel = 1. Start a new game and press ` or ~ and and a debug panel with various options will appear on the right side. For example, select the "Reveal All" option to view the full map.
Rather than randomly selecting a successful looking civilization and sending spies on a whim, look to the intel that is provided more carefully. Check for possible trade routes where you'll gain science knowledge through trade to send a spy to that civilization and improve yourself using more devious measures. It's a great way to avoid wasting resources.