Just a small correction, Neptune Aquatics is in Milpitas, CA. Our club San Francisco Bay Area Aquatic Plant Society had one of our meetings there in 2011.
if you want something out of the ordinary you may want to look at Celestial Pearl Danios. I have 7 of these. Gold Ring Danios are nice also. They may be more expensive. But Neptunes is a good resource.
EDIT : just saw you already have 4 Zebra Danios, they'd be too boisterous for the smaller shyer Danios, so ignore that suggestion.
Is the shell aquarium safe ? I'm always worried they'll add bad things to my tank, change the PH etc...
You can tie Java Fern to your driftwood if you want to try a super easy live plant.