I am planning on visiting MK, EPCOT, and AK...no sweat if I don't get to MGM...this will mark my 40th visit since September, so I am in no big rush to get the attractions in...I plan on buying her an Annual Pass so if she doesnt get all of the attractions done, She will in due time. I really am looking to create an awesome time with "resort based/nighttime/unique" experiences...I like all kinds of food (heck if the San Angel Inn Cantina was romantic enough I would eat all of my meals there)...
OK, THIS might sound like I'm being a wet blanket, but unless you guys have been together a good long while, or you know she's a Disney nut too, and unless this isn't your first trip together anywhere, I'd suggest buying her a parkhopper now. If you guys have an awesome time together, then after the 2nd day, you can ask her if she'd like to come back with you sometime soon, and if she says Yes, THEN upgrade to the annual pass.
Not trying to quelch romance, but buying her an annual pass pretty much says "I expect to come back here with you," and if the trip doesn't go as well as you'd hope, or (knock on wood) you guys start having problems, you don't have that fairly expensive present hanging over your head.
But if you guys have been together a while, and she enjoys WDW like you do, then I'm sure none of my concerns factor into your situation.
Oh, and one suggestion I forgot to make before...if you have the scratch, and if they're occurring during your trip, consider getting tickets for the Pirates & Princesses Party at MK. Since you're only there for a few days, having 5 hours in the park, when it's darker, and without the heavier crowds you'll often find during extra magic hours, could be a plus in getting some of the bigger attractions under your belts (I know you go often, but I don't think you mentioned if SHE goes often, and she might like it).