With each player in a game of Scrabble or Words With Friends getting 7 letters at a time on their rack, 6-letter words can play a huge part in deciding who will win and who will lose a game.
The 6-letter words containing AT on this list are worth 9.1 points on average.
But the best of the lot is worth a grand total of 24 in a game of Scrabble and that word is IZZATS.
If none of the 763 words on this list meet the criteria that you are looking for then you may find some success with similar lists: 6-letter words starting with AT, 6-letter words ending in AT and words with AT.