We leave DS at DC every day and some days/weeks are harder than others. Generally, we try to make goodbyes, quick and loving and then we don't look back. We say, bye, love ya, have a good day, give him a hug, and leave. He warms up and gets entertained with other things soon enough. Also, with DS, often milk or a small snack will distract him. IMO, leaving LOs is a part of life and is just something you and they have to get used to.
I agree with you, and I personally think that mom and dad need time together too. We're doing date nights once a month and it's nice to get away and spend time with each other and he does fine with my sister which is great. The day care people said to just keep taking him and he'll get used to it eventually. Thanks for the advice!