So what are the dimensions of the area you have for the trees? I ask since growing multi-variety trees I think works better if you have more width. Otherwise, I think you are better off grafting one type on top of an existing tree to give you 2 varieties. I’ve done that with some pears I’m keeping rather narrow because they are next to a path. That seems to work well for keeping the tree balanced through pruning while letting each variety have enough growth that they should be productive. Otherwise, the varieties I tried grafting on lower branches just don’t get the vigor to do much, particularly if the tree is on dwarfing rootstocks.
For specific varieties, I’m in Arlington, VA and I have Girardi Mulberry which is dwarf, tasty and produces a lot of fruit for its size, so probably the best for your situation. I would keep that a single variety.
For peach, I like Contender since it seems to do better with the late frosts we’ve been having that nuke a lot of stone fruit around here. It doesn’t get as red, so I have heard it is less of a target for birds as well. My 2nd leaf tree set a lot of fruit when most trees I saw in the neighborhood and at the community gardens were either bare or only had a few peaches. Of course, squirrels got the peaches, so I need to work on that. You could graft a early season peach to it, like Earliglo or GaLa, or you could try a plum, but apricots are for sadists.
For pear, I like Seckel a lot, both my current young tree and others my mom grew when I was growing up. Harrow Sweet is productive quite early and has a great reputation. I really enjoyed the few I bought from a vendor at the farmers market. I have 2 HS trees and they set a lot of fruit this year, but I didn’t spray or bag in time and their were codling moth larva in all of them before I knew it so I cut them all off and haven’t gotten to taste them from my own tree yet. If I had just one tree, I’d do Harrow Sweet on the bottom (on OHxF87 rootstock) and graft in Seckel to the top at about 6 feet. Seckel is naturally dwarfish, so that should help keep the size down. Seckel are also harder than most euro pears so seem less of a target for bugs in my limited experience. Both of these will ripen on the tree without rotting inside, which is a big deal for me, since the whole pick them early and store in the fridge, then counter to ripen routine is too confusing.
And of course there are Asian Pears. If you like their flavor and texture, I’d actually do one of those as well, probably Korean Giant, because I think pears are generally easier than many other fruit so it is nice to have something easier to be successful with. You could put 20th Century or another variety on top for something earlier in the season. Pears are super easy to graft, so even if you are just starting you should be able to make it work most of the time. Many pears take a long time to start baring fruit, particularly some of the euros, so the ones I listed above also fit my impatient nature.
I don’t have Jujus, but I think the suggestion of going to Edible Landscaping is a good one. From what I’ve read I would probably go with Li, but again, I have no direct experience.