I liked the Silver/Gold remake. But remember it is still silver and gold. They don't add anything, really. If you want to replay Silver/Gold, get it. If not, don't.

As for 3DS, get NSMB2. Kid Icarus is supposed to be good, but I never played it. It had a bit of production work into it, even though I hear it's on rails.

Kingdom Hearts is always a good investment if you are a fan of the series. If you haven't played it before, you may want to skip it.

B&W2 is a straight sequel to B&W. Hence the 2. Same characters, elongated story. I hear the story is pretty legit. It's more in-depth than the first. But I personally never played Pokemon for the compelling story, so I can't see it being that much different in many other aspects. But from what I've read, good reviews.