Coming from the girl who overthinks and worries too much about absolutely everything: don't worry too much about socializing to what and where and who and how many times! It's important, but so many people stress about it. I know I did with Dance and even the Dobermans and if anything, as a result, I forced too much on them by accident probably. Any list of goals and ideas I had for Journ honestly got thrown out when I got her. Puppies all mature and grow differently. I didn't have time for lists LOL. And once she was home, they seemed pretty useless (for me).
I didn't specifically seek out certain things for Journey. I took her downtown, where there are weird statues, crazy people, costumed people, normal people, big people, small people, smelly people, clean people, construction, buses, trains, people yelling, bicyclists, roller bladers, skateboarders (yes, even in winter) etc. I gave her treats, played with her and just acted like it was normal, relaxed every day life. I took her on the bus (which is squishy, dark and cramped and full of people), to work (which really didn't IMO do a whole lot for exposure, but was just nice to be able to do), on the train, to the train stations, up escalators, in elevators, around other dogs I knew, to different peoples' houses, to my Dobe breeder's house (hectic, doggy, busy) and really I don't think I went out of my way to take her anywhere I wouldn't normally go. Mostly because downtown pretty much exposed her to all kinds of weird things anyway. Weird things are definitely important. Oh, and I didn't force her to interact with anything. People were a given since she's a people magnet and everyone feels compelled to touch the fluffy puppy, and she loves people too, but otherwise I just kind of had her around things without any direct interaction. And when she went through like three days where she was leery of people, I just tossed treats at her around people and told people to leave her alone and everything worked out super well and she's my most stable, do anything dog I've ever had.
The ideas you have are good ones if those are the types of things he's going to be around.