I play a townhouse like an apartment. The couple next door are pretty much left alone direction-wise. I did play them until I got them to the point that I figured they were naturally/realistically skilled and able to have lives, so to speak.
The biggest problem is that they will occasionally route fail trying to get to something they figure is closer, but is in the other townhouse. I assume the game is capable of totally stopping this, as it isn't a problem that I can tell happens in San Myshuno. But it happens about once a Sim day at least. It seems to do mainly with the fridges for some reason, maybe since the inventory of the two fridges is shared.
Another problem I had was with locking and unlocking the doors when guests came over. That was a huge pain, and they'd keep going in each other's houses then, too. I solved it pretty much by putting their friends in a Club with them and using the Allow Club Members door lock option. I have to put new acquaintances in there if I think they're going to be coming over. I have her and friends in one Club, him and friends in another, so that I have more club slots. And when I have an Event at the house I have to stop and think if all the guests can get in. Allow Employees seems to let the caterer, etc, in.
There is a new door lock mod on MTS now that allows you to pick community Sims that they know, to let in without unlocking. It is similar to Scumbumbo's old door lock mod that started causing some problems, altho it doesn't have age groups. So I may try that out on this lot.
The next door couple's friends do come over autonomously, which is nice, and they let them in about half the time. :)
Otherwise it works semi OK. Sometimes the neighbors will get home from work and just stand outside for a couple hours. They must be gathering up the courage to go in, haha. I have them in a Club by themselves as well, which is gathering about all the time. Activities are eating, sleeping, cleaning, repairing, cooking, bathing, etc. Their Needs get a little low sometimes, but they seem to finally care for them. They don't really do their daily work Tasks, but they are high enough in their careers that I'm fine with that. He, being a Painter, still paints all the time. She is a Trainer, and works out a lot.
There is one part of the house that is accessible to both families, a game room/bar in the basement, so they can socialize if they want. They're always eating together on the patio and hanging out at the firepit as well. :smiley: