Kevin DeYoung posts on Why Memorial Day is Worth Remembering (h-t-Justin). DeYoung gives five good reasons, and it's worth a read.
I'd just add a sixth reason: as Christians, we must never forget that our freedom in Christ is not free. It costs us nothing; it cost Jesus everything He had to give. Jesus "loosed us from our sins by His blood" (Revelation 1:5). He gave His soul, His life, His shed blood, to pay the price to set us free (Matthew 20:28).
The freedom purchased for us Americans by our soldiers is of infinitely less value, that is true. They were not spotless and pure as Jesus was, also true. Not all died completely voluntarily as Jesus did, also true.
However, that I can homeschool my kids and worship publicly where I choose; that I still have some degree of freedom to criticize the current administration;that my native language is American English instead of German or Japanese or King Georgian English or Arabic — this freedom is not mine for free. Other men died that my family and I might be assured this freedom.
It's worth a day to recognize that fact, and pray for our living troops that more of them not be honored by it next year.