Welcome to AA! Congrats on the proper aquarium. You've came to the right place to get great advice and inspiration to help bring your tank and this hobby to the next level. You should post a thread in the Getting Started or General Discussions FW
sub-forums about stocking ideas, as you'll get a lot of perspectives and options to choose from.
I think a nice school of small fish like tetras or rasboras would be nice. One of my favorites are ember tetras or galaxy rasboras.