Obligatory link:
IMHO, two spaces between sentences doesn’t look better or enhance clarity, which is probably why virtually every bit of typeset print that everyone here has ever read in their lives only has a single space between sentences. Look at any professionally-produced magazine or book if you don’t believe me.
You only see two spaces in monospaced, typed documents and word-processed documents by people who still think that the modern word processor is a typewriter.