I am not the greatest fan of the Big Blind. Who knows what a single bettor raises on! Yet, AK are really good hole cards. I would normally raise 3 x BB on a 10, 9, or 8 table.
Below these configurations, for instance, tables with 7, 6 or 5 players, I might be more conservative and flat bet. The reason for a flat bet on the middle size tables is that many pairs, high or low, go through and win the pot against over cards.
I have seen the same thing on lower size tables such as those with 4 or 3 players. AK is a nice catch, but it is still not a pair. Flat betting offers a chance to see the flop before making a high chip commitment. I would follow this procedure not just with AK and AQ, but also with AK and AQ suited.
When it gets to Heads up, a more aggressive approach is probably appropriate, meaning go 3 x BB on AK or AQ, suited or not, because over cards often rule when pairs are scarce - just don't count on it as gospel.