I think Genie plus actually works best with park hopping. The schedule below shows how I stacked LL's on a crowded June day where we rope dropped DL, hopped to CA at 1pm, took a long hotel break from 3-8pm, and then went back to DL from 8-10pm. Basically, while we were at DL in the morning, I was "stacking" LL's for CA for 1-3pm. And then during our afternoon break, I "stacked" LL's for DL for 8-10pm. (I also purchased ILL's for Rise of the Resistance on this day. You can buy those anytime, independent of when you get your
Genie+ LL's.)
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While waiting at the rope in DL: got LL for Guardians of the Galaxy with return time of 1pm (even though the actual LL return time was 8:15am, we automatically got a return time of 1pm since that's the earliest time you can hop to CA)
8-10am: Rode our favorite DL rides standby with almost no lines: Big Thunder, Indiana Jones, Jungle Cruise, Haunted Mansion, Buzz (Pirates was closed or we would have done that too)
Checked on Rise of the Resistance ILL return times every now and then--bought them around 9am when the return time was 11am
10am: got LL for Soarin with return time of 1pm
10:30am: Went to Galaxy's Edge and enjoyed the ambience. Rode RotR with our ILLs. Rode Smuggler's Run single rider. Had lunch.
12pm: Got LL for TSMM at 2:30pm
12:30: Walked to CA
1-3pm: Entered CA and rode Soarin' (LL), GotG (LL), Radiator Springs Racers (single rider), Incredicoaster (single rider), TSMM (LL), and Grizzly River Run (single rider)
At 2:15pm, got LL for Indiana Jones with return of 7:15pm
3pm-8pm: back to hotel for nap, swim, and dinner. At 4:15pm got LL for Matterhorn at 8:30, at 6:15pm got LL for BTMR at 8:30
8-9pm: Back at DL, rode Indiana Jones (LL), Big Thunder (LL), and Matterhorn (LL). At 8:15, used the refresh trick to get LL for Smuggler's Run with return of 9pm
9pm: Went back to Galaxy's Edge for a night view. Rode Smuggler's Run (LL)
10pm: Rode Star Tours standby with no wait as we left the park.
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In all, we rode 18 rides, and never waited more than 20 minutes for a ride. And I didn't feel like I had to be on my phone all the time. I just set a timer for 2 hours later each time I made a LL selection. When the alarm went off, I looked over all the current return times and picked the one that was farthest out that fit into the hours when I was trying to stack rides (1-3pm in CA, and then 8-10pm in DL). If you look through the list of rides and none of the return times work for you, just wait a bit for the return times to get later, or if you want an earlier return time, try refreshing the screen a few times in case someone else cancels their LL for the time you want. And remember if your LL time is 2pm, you can check in for the ride any time between 1:55 and 3:15, so that gives you a lot of flexibility.