(Apologies if something similar has been posted already...)
I'd love to see more chances to build up central/urban areas in the DLC. The houses around Bunker Hill, for example, are pretty much in-tact. Why just keep people in shacks? Wouldn't the SS try to build an administrative center like Goodneighbor? Supply lines can provide an exchange of goods (ie. crops), much like those in the Roman Empire. Perhaps this option could unlock after a settlement reaches a certain population level?
It would also be good if the DLC clarified what effects many of the items have on settlers' happiness. For example, I've read that TVs increase settlers' happiness online, but there's no mention of it in the Survival Guide. Perhaps quests to obtain useful or helpful items could be added.
I'd also love to have a simplified way to see who has been assigned to what. I currently have to manually search crops and stores, and manually assign people to them. This is OK with a small settlement, but becomes cumbersome as the plots expand. I also don't always remember who I assigned to what... (If there's a better way to do this, please let me know!)
Expanding Home Plate's utility would also be useful. If it can't function as a normal settlement, why not give it some extra items and/or options for customization? It's not super useful at the moment, especially given all the options for fast-travel.
Bodies need to be easily removable, too...