The Country Light Candle Company (first link below) has a line of long-lasting candles, such as 7-hour tea lights and 15-hour votives.

If you prefer to go out candle shopping instead of ordering online, I've also linked to a guide to judging whether or not the candles you are viewing are long-lasting.

Here are some 7 day emergency candles.

Beeswax candles are the longest lasting candles.  You can find some using the second link provided below.

There are many that last a long time. I found that beeswax candles do last the longest and that "all types of quality candle waxes have been shown to burn cleanly, safely and in the same manner. U.S. candle manufacturers select waxes or blends of waxes based on their suitability for specific types of candles or formulation profiles, as well as their own candle-making preferences."

Helpful hit: I have been told that if you freeze candles before using them it makes them last even longer. 

Here are some additional links that I found for longer lasting candles.