I am using Bootstrap theme, attempting to build a basic skeleton site that will use Nice Menus dropdown. Cannot get it to work: if putting in a block it displays alongside main menu, if disabling block and enabling Nice Menu 1 in Structure -> Blocks it does not behave correctly, no dropdown on hover
Nice menu works in same way as you required. Did you configured this module correctly?
First you need to look into configuration of this module(Nice menus).
After that you need to configure your nice module correctly in block list as in attached image. If still error persists then look for JS error.