Every time I've gone to Vegas I've gone in the summer - last time was 2009 - and on that trip, and the couple years previous to it, they always waited about 15 min. between launches. Not sure about hotel guests complaining about noise, but the ride ops explained to us that it was due to the heat since in July and August (when we were there) it tops out around 100 during the day and still around 80-90 at night... Don't know if year-round they do the 15 min. wait, but every time I've ridden it in the summer months, there's been space between rides.
Top 5 Steel: Bizarro (SFNE), Top Thrill (CP), Montu (BGT), Kumba (BGT), Cali. Screamin' (DCA)
Top 5 Wood: El Toro (SFGAdv), Boulder Dash (Lake Compounce), Lightning Racer (Hershey), Beast (KI), Yankee Cannonball (Canobie Lake)
Total Credits: 122