They carry almost every US blu-ray and HD-DVD title in print, including TV shows
Like with DVDs, if you get a disc back on Monday you'll almost certainly get a Tuesday new release, but if you miss that window it goes to short/long wait for a while. After the initial rush most titles are "now" or "short wait."
This assumes you aren't being throttled for renting 20 discs a month, I can't say how it works then.