My personal philosophy of "valuable life" (summarized):
1) Sapience (rational intelligence) is valued, no matter what species possesses it.
2) The assumption of sapience assumes that the species must make some intention of using it, and is capable of reason. (This assumption would hold true for any space-faring species, at least at some point of their development. It's impossible for them to have achieved space travel without some form of cooperation, simply due to the scale of the sciences involved, and cooperation is a social function for intelligent beings, ergo, reason must exist.)
3) Following 1 and 2, if communications or appeal to reason break down entirely, that's when I resort to more difficult methods: Is it more cruel to imprison indefinitely, to execute, or to study the species.
Depending on how the situation unfolds, a more pragmatic response might be necessary.
Keeping in mind, that under these values, individuals and organizations who are capable of reason are held to their actions regardless of species or race. Any sentient being who makes choices must deal with the consequences.
EDIT: Changed wording for accuracy.