Just a comment or two amongst some very well considered responses.....
Long Range Cruise (LRC) is a 'convenience' speed from a bygone era with not much practical application in the current high fuel cost era. As stated, it provides 99% of the Optimum Range available at Maximum Range Cruise (MRC). For those aircraft with which I'm familiar, CI=0 at MRC, although between different types CI's above zero are a bit arbitary, varying from type to type.
As Intruder has indicated, there is never a case where MRC could possibly be below Vmd, Minimum Drag Speed, and will in all cases, including cruise at well off optimum altitude, be somewhat above it. Vmd is for all practical purposes the best holding speed. Intruder, you have me a bit puzzled when you say "Note that the FMS does not take into account wind differences at different altitudes, so some other way to determine best altitude for the wind profile must be found". Perhaps so with the generation of the FMC/FMS that you're using, but, if a good range of winds for several thousand feet above and below the theoretical optimum altitude are inserted in, at least modern generation FMC/FMS units, the recommended altitude WILL consider wind gradient. It's not uncommon when pushing into a strong Head-Wind to see the recommended level drop to a lower level if all of the winds at all practical levels have been inserted. If only one wind has been inserted, the FMC/FMS is pretty happy to stay where it is and suffer the penalty.
With respect to the last two posts (Jambo Buana and Intruder), again for whatever CI is chosen MRC all the way through to High speed, if a full range of winds are inserted, full compensation is made for adjustment to the zero wind speed at the current level, and recommendation to an alternative level if the gradient indicates so.
Regards,
Old Smokey