This is a rehash of existing threads...
Summary from what I can remember of the generally popular/accepted ones:
1) Projector [HID/LED] headlights (self leveling even better) $$$ (but worth it)
2) Cruise control $0
3) Larger fuel tank $0
4) LED lights all around (brake/turn/markers) $0
5) Larger, color computer screen with more simultaneous readouts and options $+
6) Mirror mounted turn signals and marker/running lights $0 or minimal
7 ) Ability to turn off linked brakes $0
8 ) TPS that has external batteries $minimal
9) Built-in rollover/crash protection bars or at least mounts for them $minimal for mounts or $$ for bars
10) Throttle by wire $required at this point so it doesn't matter
But just as important, the DO NOT CHANGE:
1) DO NOT TAKE AWAY THE ANALOG SPEEDOMETER AND TACHOMETER!
2) Don't change the shaft drive, it really works well.
3) Don't make it heavier.
4) Don't make it any taller.
5) Don't mess with the transmission- it is super nice.
We could go crazy with lots of exotic things (active suspension, electronic suspension, remote locking of bags, proprietary GPS, etc), but the bike would cost as much as a BMW
Well, maybe not THAT much....