Barking! Barking! Barking!

Question
I have a 7 month old long haired dachshund. He's a tweenie/small standard.
He barks at people when:
1. they try to pet him on the street
2. they are moving around the house, even if he has already seen them, been
held/fed by them, etc.

He is VERY well socialized. I live in a large city with many dog parks (and
people). He's great with other dogs and if someone has a dog with them, he's
very likely to accept their petting. He rides on the subway with me, goes to
the pet store, goes to TJ Maxx/Target/etc.

To correct the barking we have tried:
Teaching him a "calm" command
Spray bottle
Penny can
Pet corrector
Citronella spray collar

The best thing so far seems to be having him wait for a treat because he's
more focused on the treat than anything else, but especially inside the house,
it's hard to get him to snap out of the barking when someone comes into the
room.

Answer
This is a tough one as there is a lot of advice and on some dogs it does not help.  I have one that I tried it all with and it did not work.  He knows I mean it when I say stop barking in a loud, firm voice and he stops but only for a minute and then he tried it again.  It is a battle of nerves with us - I have to keep at it until he finally decided he will not push me.  I do NOT hit him.  I almost yell but say it in a deep tone that lets him know I am angry about the barking and he looks at me and stops.  I tell him no bark.  Barking can get to be a problem and if you have neighbors it is something to be concerned about.  Keep trying and be persistent.  Let him know you do not like it and I hope with time he will come around.  I know that is not a lot of help, but sometimes it is such an issue and he is young so he can learn.