Under the current rules, there is no advantage to being onsite when it comes to Genie+. With regard to purchasing ILLs, there is an advantage to being onsite, but no distinction between deluxe resorts and the moderates and values. Disney has announced, in very vague terms, that there are changes coming to Genie+. There are rumors the changes will give those staying onsite an advantage in making bookings. However, those are only rumors at this point.
The only way I know to be able to book your second G+ LL at 9:00 would be to get a first G+ LL with a return time of 9:00-10:00 and tap in to it at 9:00 sharp. For a desirable LL, you'd have to be very fast and lucky to get a 9:00 return time. You probably could get a 9:00 return time for a less-desirable ride if you wanted, but that only gets you the less-desirable ride as your "extra" ride for employing this strategy. If you're going to the parks early anyway, there can be benefits to picking up G+ LLs with early return times . . . as long as they are rides that you want to ride anyway and the LLs save you time. During the first hour after opening, the rides that have immediately-available return times probably have short standby lines too.
If you want to ride Slinky or Remy in your second park of the day without a long standby line, you may have to book them first. They may not be available at 11:00; they may not be available at 9:01.
