I have tested several plugins for social bookmarking but found many of them far too bloated and big. The functions included in Jetpack are too basic, otherwise that would have been a great option since I have Jetpack installed already.
I ended up with Digg Digg which has a really nice floating option. It’s set up to only show on pages and singe posts. I changed the positioning of the floating buttons, from -120px to -85px.
For current plugins at this site: see WordPress Plugins I Use.