What we did was this:
In her first month, when she couldn't be on ground outside of our yard, I invited people over. All sorts of people. Old people, young people, toddlers, babies. People with beards, with glasses, wearing hats, with long hair, with no hair. I didn't force her to interact, I didn't do anything: I'd have people come over, we'd sit with her in the back yard, and if she was interested in them (she often was), they'd pet her. Nothing forced. I brought out a skateboard (she would put her front feet on it and push along), showed her a bicycle. Had one of those kid tunnels out in the yard, and would roll a ball through it, and she'd go after it. I opened and closed an umbrella. Balls of all sizes. A sled filled with water.
I called our local police station, and asked if I could bring her down to meet people in uniforms, so she wouldn't be scared of such—they were delighted. We took her down, and all the officers cuddled her and cooed over her. We took her out to a squad car, and they turned on the lights and sirens as I held her, and she was just interested and fine. I took her to a hardware store (she LOVES hardware stores), where she met a man with only one leg (who had lost a Lab earlier—he saw her and got all teary-eyed), and another man in a wheelchair. I took her to my the athletics center on my campus (school was not yet in session, but the athletes were there), where she met college-age kids of all sizes and skin colors, so she wouldn't be afraid of people with skin colors other than ours (we are fairly light-skinned).
I took her on an elevator in my campus building, and she met my colleagues. I just never took her to places where other dogs had likely walked.
She met two or three vaccinated, well behaved dogs belonging to friends, in our back yard. Within the first month, she had met about 100 people. All in our back yard, or one of the outings described above. I was exhausted!
I also had her in puppy classes, where she again met a person in a wheelchair (and, interestingly, was drawn to him so much that he said "her parents musts have been service dogs") and some other safe, vaccinated puppies in a clean area. This was where we saw a lot of her personality, which is that she's a very soft dog, and really prefers people to most other dogs.
After her puppy classes, we had her in training classes for the next 8 months or so. She had both training and free play time with other dogs, but always well behaved dogs, and in a controlled setting.
She's been to dog parks a few times, but it's not really my thing and doesn't seem to be hers. I've seen some aggressive dogs, but mainly negligent owners not correcting rude of bullying dogs (seriously: humping another dog is aggressive, rude behavior—why do people think this is funny?)
As a result, Hoku has ended up an amazingly well socialized dog. But I never ask, much less force, her to greet other dogs, and I never forced her, as a pup, to engage in any potentially scary activities with objects or people. I think a good amount of Hoku's ridiculously calm and sweet temperament is her breeding, a good amount is her own personality, and a certain amount our socialization.
Honestly, she is such a sensitive soft dog—something I adore about her—that I think what we did was beneficial. As a lot of people here know, she's sort of weirdly self-conscious about any perceived wrong in a way that makes no sense to me. It's almost like she's too eager to please, and too worried about displeasing... or something. I love her softness, and she's definitely not nervous or skittish or anxious, but a high-drive Lab she's definitely not.