You should buy MLBTV...for Grape and Cactus games...
You can listen to just about every spring training game...and usually watch about 5-6 games per day...WASH/ATL is on tonight...
If you do not want to buy the package...go to MLB.com...go to the scoreboard and click the box score for the game you want...has page refresh selections on the top...that is the quickest free update that I know of.