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).
We're definitely taking this seriously. Sports is a big market and you're right it's totally underserved. We've looked at some of the more specialized solutions you mentioned and there needs to be something much better.
One of the things we're working on to better support sport teams is helping with roommate assignments. We've done some of this manually so far and know how painful it can be, so now we're building it into Roomblocker.
We'll be doing outreach to tournaments, leagues, and teams - if you have any contacts would be great to connect. Either way, thanks for your help!