If it were me- first think I would do is train her to laydown and stay any time someone knocks/rings a door bell. This way you can greet your visitors in while Cali is in her "spot" and tell them not to acknowlage her until you release her from 'stay'. After a minute or two allow her to come and greet. By this time she should have gotten over the excitment and be able to calmly greet your guests. It's a great idea to have her spot be a rug or something you can bring with you so you can employ the 'stay' when you visit other peoples homes. Of course you will have to do this slowly. This technique also works well for any time you need to open the door and don't want the dogs in your way, or bolting into the road. If you are concerned about giving too many treats, a GREAT way to work this in is don't give 'treats', but use your dogs regular dog food. Take a handful out of his/her usual daily food allowance to use for 'treats' then you aren't giving junk.
Start by having someone come over to help you. Tell them the "rules" no eye contact, no speaking, no aknowlagment of ANY kind. Have them do this just as if it were any other visit -knock/doorbell- and have Cali go to her spot. Have her sit/lay and tell her 'stay', 'wait' whatever you prefer, and slowly go to answer the door. If she gets off the spot, immediately go and correct her, telling her again sit/lay and then stay/wait, go to the door, and if she gets up immediatly close it, and repeat sit/stay sequence until you are able to have your guest come in and sit on the couch or what every you prefer without Cali getting off the mat before you signal her to do so.
If you havn't begun 'stay' command, then obviously that is the first step, but teaching her with her 'spot' will help her recognize her boundaries-where she has to 'stay'. I'm teaching this to my dogs...well MY dog, Sampson, (poodle) and my husband's idiot dog, Zeus, (not sure what he is, but what ever it is it's big, drooly and dumb as dirt), who bolts out the door running over anyone/thing in his way when the door is open. It's comming slowly, I have to train them individually since they are more interested in playing when they are together.
I know this works-I've seen it first hand, but you MUST be consistant and realize it will take time. Untill then, keep Cali on leash when you are visiting or having guests over. This will give you control over her until you are able to make some headway with the training
Best of Luck!