My husband & I plan to spend one full day in Brooklyn during our upcoming NY trip. We definitely want to see Brooklyn Heights & the Botanical Gardens. What are other "must sees"? Any suggestions on good Walking Tour companies? Any suggestions/hints/tips will be much appreciated!

Definitely visit the Brooklyn Museum of Art, which is right next to the Botanical Gardens.
http://www.brooklynmuseum.org

While you're in Brooklyn Heights, visit the Promenade for great views of Lower Manhattan.

For walking tours, pick up a copy of Time Out New York magazine from a newsstand when you get here. They'll be listed under "Around Town". Have a great trip!

Don't forget about pizza at Grimaldi's.

I'm a big B/lyn fan. Everything above is worth the time. Finish your day with a walk across the Brooklyn Bridge, as the sun goes down, from the B/lyn side toward Manhattan. Statue of Liberty, ferries going back and forth to Staten Island,walkers, bkers, jogers all share the bridge so follow the arrows on the walkway. Of course the Bridge itself is a treat in itself.

Ok live in Brooklyn, so I can vouch for some things. There is a Gray Line bus tour of Brooklyn that someone mentioned. You can also check out downtown Brooklyn for shopping, check out Juniors on Dekalb and Flatbush Aves for the most amazing cheesecake! You can also check out Prospect Park and the restaurants and places in Park Slope.

I suggested to one person to check out the tour of the Brooklyn Brewery in Williamsburg. If your day is a Fri or Sat, they have an open house from 6-10 with $3 pints of beer, live music and art showings. Good to check out even for a little while and some cool shops and cafes in the area as well.