Alrighty, here's a rough inventory of our non-automotive toolbox. Keep in mind this is more a result of what we had kicking around the house than of careful planning; some things are here simply because they don't really fit in anywhere else. There are other items we obviously use that aren't listed here because we both know where they are stored.
Top (half width) tray:
Small can WD-40
Safety glasses, yellow (easier to find when dropped!)
Telescoping mirror
Electrical tape
Stud finder
Outlet tester and chicken stick
Stainless steel ruler
Tape measure
Utility knife
Pencil
Chip brush
Main tray:
Screwdrivers: stubby, small, medium, and large, in flat blade and Phillips, plus a mini/eyeglass set
Pliers: standard, mini needle-nose, slip-joint
Wire cutters: standard and mini dikes, mini nippers
Vise grips
First drawer:
Staple gun and staples
Claw hammer
Assorted nails and screws
Second drawer:
Chalk line
Masonry/landscape string
String levels (2)
Drywall saw
Wall anchors
Torpedo level
Third drawer:
Adjustable wrenches (6", 10")
Pipe wrench
Pipe cutter
Plumber's tape (strap)
Teflon tape
Faucet grease
Putty knife
Wood chisels (three small)
The above could be improved or at least better organized, but maybe it is at least a little helpful. Obviously some of these are of no benefit to you on the road.
Outside of the occasional 1/4" and 5/16" hex head fasteners, I don't remember the last time I used a socket on a home repair job, but a cheap and basic 1/4" drive ratchet and socket set might be cheap insurance if you're going to be away from home with this bag. I would also throw in a basic imperial Allen key set just to cover by bases.
A speed square, as SV reX suggested, is a smart idea. A Leatherman, or at least a good SAK + pliers combo, in the pocket would also be a great safety net. And a flashlight. I have a ~$30 USB chargeable Anker unit that is compact enough to carry in a front pocket and is plenty bright.
We also have an M18 drill and 1/4" impact driver like you listed, and I think those will probably end up in their own dedicated bag with a basic drill index and driver set. That way they are still organized and portable, still readily accessible for automotive stuff, and not eating space in the main/home tool bag.