You said you want it to be as close to perfect as possible. Well, you're 90% there by picking Negril! I am not an AI person, so cannot comment on any of the AI's, but go for it! Do what you feel comfortable with ... I guarantee there will be other trips after - Once you go, you know! The boardies here are a great guide. Better than any travel agents.
If you do stay at an AI, get in touch with the One Love Bus Pub Crawl, and do that. It takes you up to the cliffs to see what is up there, and aside from a spectacular view, there are great bars, awesome restos and the nicest people on the planet to chill with. OUr fearless leader and great guru of all things Negril, Rob, can point you in the right directions for this! And more. It can be crowded, but that's half the fun! AI or not, I would heartily recommend a dinner at Rockhouse or Catcha Falling Star Cliffs (Ivan's). She will love you forever after one of those! (Coconut chicken at Rockhouse is to die for!). Blue Hole at Roaring River is an awesome trip. There are so many "not to be missed places" that you really need to start planning trips 4, 5 & 6 to get it all in.

Oh. You need to send us all a trip report! There is nothing more uplifting than reading a new visitor's take on our beloved Negril! Watching somebody fall in love! Please do.
Just one word of advice. RELAX. Enjoy. There's no hurry. No problem, mon. And BTW - Jamaican 101. "Soon come" has very little to do with "soon"! But hey, who cares!
You're in Negril. Take it slow!

Cool Runnings, Fozzy and the soon-to-be-surprised Mrs. Fozzy!