My golden keeps jumping on guests - how do you all handle this?

Our 18-month-old golden, Biscuit, is the friendliest dog on the planet but she has absolutely zero concept of personal space. Every time someone comes to the door she loses her mind and launches herself at them. My mother-in-law got knocked back into the doorframe last week and now my husband is getting pressure to "do something about it."

We've tried holding her back, saying "off," turning our backs on her. She'll calm down for like 3 seconds then goes right back to it. I feel like we get some progress during training sessions and then company shows up and it's like we never started. Do goldens just take longer to learn this? She knows sit and stay no problem in normal situations, it's just the excitement of a new person that makes her brain short circuit.

Anyone else been through this? What actually worked for you?