This is a child who gets only A's and whose GAI is >99.9% on the WISC IV. What is going on with her? Is she really finding the work hard, or is something else at play?
Rachel, there could be so many different reasons your dd is saying the work is "hard" - none of us can tell you why, you'll need to really listen to your dd and also think through the details of when work is said to be hard, what's going on, what type of work, etc.
The thing that jumped out to me from your post is you told us you're dd's GAI, not her FSIQ. Your experience may be different than my experience, but the psychs we've seen for testing don't report a GAI unless there is a certain statistical difference between FSIQ and GAI - so I'm guessing there is *something* on your dd's WISC in either the Processing Speed section or Working Memory section that lowered her FSIQ relative to GAI. If that's the case, she might really be experiencing "hard".
Do we leave her in her school where she appears quite happy overall, or should we move her to a gifted program?
I'd try to really understand what she's saying is "hard" before making a school/program change decision.
She is obviously extremely bright but perhaps not always self-motivated. She has also said at times that very few kids "get" her, though she does have friends. What would you do with a child like this? She appears to be happy but maybe we're missing something?
The things your dd is saying sound like things a child who is feeling awkward, out-of-place or anxious at school might say. On the one hand, with a very bright child, it's easy to see this might be due to the difference in intelligence - but it's also exactly what my 2e kids have said when they were around the same age struggling with challenges related to their 2e prior to diagnosis. Soooo... absolutely, I agree, you need to try to do something to help her out - but first you need to figure out what exactly is going on.
My advice is to look back at her WISC test - what type of difference do you see in PRI/VIQ vs PS/WM? Did the person who did the testing note any potential reason for the discrepancy? How long ago was she given the WISC? If you see differences in individual subtest scores, look at what those subtest scores measure (or post them here) and see if any of the dips correlate to the types of work she's saying is hard at school.
I'll also second master of none, tallulah and dbat's posts

Best wishes,
polarbear