I am interested in, and have started working on, a program that looks at a users collection of sheep and attempts to find the longest simple path through the collection. This would reveal the longest sequence of seemless play. Being that this problem is closesly related to the Hamiltonian Circuit/Path problems (NP-C) it would be very computation heavy with larger collections. So the effeciency of the algorithm is crutial and anything that can be done to increase this would be very helpful.
Does anyone have any thoughts, suggestions, or advice they could provide to help me with this task? Has this already been done, or at least partly done? I know there is a seemless playback function of the new ES software, but it doesnt work very well, if at all.

yes the seamless option is
yes the seamless option is broken on windows, and the fix will come in the next release (soon).
i am not sure what you are really after, but if you don't allow repeats then you will disallow many practical sequences, and if you do allow them, then the longest path becomes meaningless. maybe a better defined problem would be to find the shortest path that covers the whole flock.
but i expect for practical sizes of flocks optimal solutions to both of these will be intractable.