limping from early position is good in a passive game where you are almost guarenteed a cheap flop.

Limping in an aggressive game where you will usually have to fold to a raise is a leak (Calling the raise is an even bigger leak).

I limp suited aces from late position if it is unlikely to be raised (and from early position ONLY IF it is unlikely to be raised.)

Alot of your value from small suited aces like A3 comes from stacking a smaller flush so a multiway pot is good.

Ill often raise ATs from late position though since your kicker has a good chance of being good AND you are likely to be in position post flop.