You and your DH may well be the only people on the planet who do not know who Elmo is.
Elric and Clinton would be strange choices.
Elmer is Elmer Fudd. You can't do that to a child.
Emmett is basically an Irish surname name inspired by the patriot Robert Emmett. And also the Lego Movie character. I don't think 50s America at all when I see it.
Anton is another Irish name - translates to Anthony. It's also Anthony in a few other languages (German, Russian, Swedish, Norwegian, Danish, Icelandic, Dutch, Bulgarian, Ukrainian, Slovene, Macedonian, Croatian, Romanian, Estonian, Finnish)... I think it's my favourite of your boy list though I like Gabriel too. I don't think it's all that popular. It was about 10 to 15 years ago around here.
Everett is nice..
Would you consider Ivo?
How about Grover? Good old Dutch-American name... 
I love Susannah, Helena and Louisa gorgeous names imo.
Dislike Erica.