A Hennessy Hammock is my shelter of choice if it is going to be around freezing or above at night. Neither hammocks or tipis have floors and you don't have to crawl to get in them.
It was southern US/Central America heat that led me to hammocks, but with quilts/underquilts they can be used down to zero without issue.
You can also hang the tarp first in a downpour and your sleeping gear stays nice and dry.
A hammock (and the knowledge to use it well) has SHTF/Urban Evader applications as well.