Teach them to bark on command, and then give them a cue to stop barking. I say "thank you, that's enough," or, put my finger to my lips, and they stop. Alert barking is A-ok, but two barks is enough! LOL

When you enter your house, how do you interact with the dogs when they're barking?

 

one dog knows how to bark on command, and he only barks once when you tell him to.
we have tried several behaviors when entering the house as they bark: ignoring them (barking usually subsides quickly, but one dog starts whining), also firmly telling them to stop (this doesn't seem to be any more effective - probably because they don't know the stop command).
their barking starts when they hear our car outside, or hear us in front of the house and doesn't stop until we're inside, so it's impossible to correct the barking immediately. and when they bark while we're already inside the house (usually at something they hear outside, and it's not nearly as often or incessant) we tell them "no" immediately and that stops the barking.
i don't know if they are too territorial or anxious or bored.

 

This is normal pack greeting behavior. As they stop on command and after you enter the house you really can't expect more out of them. You're doing the right things. Some dogs are just less vocal in their greetings depending on their personality or breed.