I think the embargo should end - completely. Not just softened; not because I think it should end in the name of "human rights" and "self-determination", which are terms that I think have mostly become empty platitudes and pious camp, but because the Soviet Union is DEAD. The embargo made sense during the cold war when the Soviet Union existed and heavily funded movements - and regimes - in Latin America that were a threat to the U.S.'s vital strategic interests in the Western Hemisphere. That threat is gone. By normalizing relations with Cuba, the U.S. can prevent Cuba from becoming another satellite for a current adversary (China) that can potentially threaten their vital strategic interests. Cuba has had over half a century in experimenting with a planned economy; it's been a disaster, just like every other planned economy. The Cuban regime, I believe, deep down knows this, and ending the embargo could probably speed up the process of Cuba moving away from that type of economy and trying some political reforms.
Yes, I am coming at this from cold, real-politick. It smacks of Machiavellian realism, I know, but I am convinced that realism is the correct approach for states in international relations.