Others will add more insightful responses but here is a start:
Leatherman- Wave, or pulse
A set of metric sockets 3/8 ratchet set is ok,
A set of metric wrenches box end on one end and open end on the other. 8mm-19mm
A large vice grip and small vice grip both curved jaw,
A set of screwdrivers, 1/4 inch flat blade, 3/8 (large) flat blade #2 phillips
A set of torx wrenches that fold up T15-T40
A cheap digital Volt Ohm Meter, electricians black tape, a 3' wire lead with alligator clips on both ends,
An ODBII reader
A tire plug kit and fix-a-flat can, a cheap compressor (Walmart)
A good rag (old towel), tube of hand cleaner
Extra fuses, 1 headlight bulb, stop and tail light bulb.
Interestingly all this will probably fit in the tire change box below the passenger seat.
A first aid kit, condoms
I would once have said an extra spark plug and socket to change it but it is not really an option anymore and won't be needed, the ODBII reader will tell you whether one is bad but you probably can't change it.
All, I can add is,
SAE wrenches and sockets
Vice grips, large and small
A set of allen keys, metric and standard
electrical tape, duct tape
couple feet of wire
windshield washer fluid
a quart of oil
Had to think hard on this one, but I conclude that you only really need two things, a code reader and a flashlight. The dongle is $15 on ebay, and I use an app on my phone that costs $9. In combination, those two things tell you stuff you need to know that the PM won't tell you: real engine temp, cat temp, actual volts, and a few other things.
But other than that, don't bother to bring any tools. Other than a screwdriver and pliers for replacing headlight bulbs, there really isn't anything you can expect to do on the side of the road. You could try to repair a hose with tape, but if you fail and it overheats, kiss your engine goodbye. Unless you really know what you are doing and plan on carrying your own parts store, I just think you'll be ahead to leave the tools at home and just plan on getting a tow.
Yea, we seem to have assumed the poster has skills to use the tools. Some do, some don't. I've done a transfer case repair on my old Samurai 20 miles out on a desert road with just my leatherman. Had to, as I didn't have enough water to walk back (the gallon jug got left on the driveway). If you know how to fix it you can sometimes improvise tools.
Just wanted to take a moment and thank all of your for the Great Feedback:
"jimmbomb" for the humor - I love a good Cigar
"RDinNHandAZ" for the list - nice tool selection
"big wally" for the suggestions - additional tools to add
"GapRunr Nitor" for the Nitro Tape - I will get some
"keeponvaning" for the reminder - 4 way, got it
"Kip-on-truckin'" for the Slap of Reality to keep me grounded as to the level of my mechanical ability (or lack there of). I think you made the best point. Unless I am a mechanic and have a bunch of spare parts, there really will not be much I can do while on the road. So, thank you all for the advice, but I think except for a few simple tools, a good AAA membership it is!
"Kip-on-trucking''" -- when you have a moment can you send me some information on the dongle you got on eBay and the name of the app you purchased. It would be greatly appreciated! Thanks
fwiw, for the last 20 years, I have been using Metrinch tools, they have a cam action on the wrenches and sockets. By design, they work on both SAE and metric. I worked on domestics, European, Japanese and even MG's (whitworth fasteners, ugh) with the tools. The chrome vanadium coating has not ever cracked.
Best of all, they fit in a small tool bag and tool roll that fit under the front seat.