I like the idea of a custom tool roll. Two sets sounds like a smart idea as well... one to always keep on the bike for shorter trips, and then a supplemental roll for longer rides.
I would include everything in the OEM kit at the minimum (not sure if you planned to do that) - except for maybe the pliers if you're including a better pair. You'll want the rear axle nut wrench (26mm on my bike) and the spanner for the shocks/neck nut.
I've found the screw drivers in the OEM kit to work very well (I think it's because the they are JIS drivers - and most of the screws on our bikes aren't actually Phillips heads - they just look similar).
You can still purchase all the OEM tools in the kit from honda... except for the 26mm rear axle nut wrench. *** EDIT - correction: you can't get the spark plug wrench either... that's really too bad. I'm not sure what would be a good replacement. maybe try to find one on ebay ***
I second (or third) the suggestions below on some sort of needle nose pliers. Very helpful if you need to install a new clutch or throttle cable and to pull out the cotter pin on the rear axle nut.... or any other situation where you just cant get your finger to fit. I always carry my leatherman, which includes a nice needle nose pliers. If don't carry a multi-tool like a leatherman on you when you ride, you might want to include one in your kit.
I use an LED instead of a regular bulb (more compact) - you just need solder a resister in series and note the positive/negative leads (it's also a good idea to add a regular diode, so the LED isn't the only diode in the circuit - at least that's what I've been told to do).
Also, I like to carry and extra 10mm wrench - I believe the pull throttle cable has a 10 set/lock nut, so you really need two 10mm wrenches to remove/install. Also, I believe the cam chain tensioner adjustment is the same way (need two 10mm to adjust) - at least on the CB750. Also, not a bad idea to have a points file and the appropriate feeler gauges if you're still using points.
I like all the suggestions below. I really like the idea of routing an extra cable on the bike... I'll have to try that. It's hard to put cables in a kit. Pull throttle and clutch are the two you can't ride without.
For the longer trip kit you may want to include tire irons and an inner tube patch kit, feeler gauges (and the smaller tappet feeler gauges), spare brake/turn signal bulb (and a spare headlight bulb if you have an H4 conversion), and a compact voltmeter/multi-meter. You also may want to add a pair of nitrile gloves, some cleaning wipes, and a towel... sounds a little silly buy whenever I have a side-of-the-road incident (most recently a flat tire on my car), I wish I had these things.
I have an F model, so I have the extra compartment under the rear cowling where I usually keep some sort of towel. I usually only use it to wipe off the seat if it's wet... but hey... I thought you were suppose to always have a towel. Maybe get a towel with "Don't Panic" printed on it.
I'd be interested to know what are the more common road side or road trip maintenance experiences are from others. From may personal experience it's adjusting the chain, replacing a fuse, tightening something (Tach cable that came loose, or adjusting the throttle cable), replacing a cable, or changing an inner tube. The last two required me leaving the bike overnight (but fortunately it happened close to home).