Not sure how serious you guys will be about it, but just know, a big tourney can mean 1k + rooms booked through such a service (incl. rooms for families for younger age group sports), and of course there are a lot of big tourneys every week, across sports & ages, everywhere (in America at least). A site only dedicated to group booking for sports tournaments could probably be it's own successful YC company (obviously with the right team). Just letting you know of this opportunity from someone who used to work in said industry (but has had enough of it).