The Aquarium is a must. Great place!
Legal Seafood is okay, but there's plenty of other places (I'd choose G&M in Linthicum, out by the airport) that have seafood as good, if not better.
I've never been to Camden Yards, as I haven't been a baseball fan for about a decade now.
Hard Rock is overpriced and extremely noisy, but I've been to worse places.
My suggestions?
Eat: G&M, if you like seafood. If you want to eat some place in the harbor, check out the Cheesecake Factory. They have a very good selection and the food is first rate.
Sights: The Inner Harbor, Aquarium, and Science Center are all good places to see, but there are other great sites. The Great Blacks on Wax Museum is nice, but it's not near the harbor (it's close to where my office is). The Babe Ruth Museum isn't that far from the harbor and I hear it's nice as well. There's also Fort McHenry, Fells Point (the Admiral Fell Inn has excellent food!!), or the Power Plant Live (where they have some nice nightclubs and the Improv comedy club, among other places).
If you want, drop me a PM and maybe the wife and I could meet you guys for dinner some evening.
Nobody has mistaken me for any kind of 'expert' on Baltimore, but since I've lived and worked in this area since 1998, I know a few spots.