Not staying onsite gets you behind all the resort guests who get in earlier than you and get ahead of you.
Rope drops are best when targeting those attractions that are the most popular and which build heavy lines very early on and stay very busy throughout the day. Your goal is to beat everyone else there before the lines explode and you have wasted time. You get as much done early on so the rest of the day you can get in on lesser attractions that may not be as heavily stacked with lines.
Those that are recommended by most are
MK: 7DMT, PP, JC, Tron
DHS : RotR, SDD, ToT, MMRR.
EP: GotG, Frozen, Soarin, TT
AK: Avatar, EE, Safari
You are going just before Christmas which is popular. LL's may be needed. Crowds are reported as being lighter than ever now but the holidays may surge those numbers up,