brunch/lunch near promenade
For Brookyn "charm" you need to walk a bit and head over to Sam's on Court for a pizza.
Other places nearby to consider are Bocca Lupo on Henry, Waterfront Ale House on Atlantic. Queen on Court has prix-fixe lunch and early dinner.
Christine's is nice in that you can sit out front on Montague St. The food is acceptable (Polish and diner fare).
Brunch options in the Heights are weak. Siggy's is great mediterranean but small and packed. Unfortunately, Noodle Pudding, Le Petit Marche, and Henry's End don't do brunch. Your best bet is Jack the Horse on Hicks and Cranberry. They do a terrific brunch, but it is Sunday --- www.jackthehorse.com
Five Front in DUMBO is nice for brunch as well although the service is so so -- nice back patio. Ditto for Rice in Dumbo on Washington St. btw. Front and York. They have an eclectic menu with Asian and Latino influence. Not a big fan of their food except their brunch which is pretty tasty -- back patio as well. Other DUMBO options include Rebar and Superfine, the latter does a bluegrass brunch on Sundays which is fun, but loud!
Another option would be to get excellent sandwiches/salads from Tazza on Clark St. btw. Henry and Hicks, then eat on a bench on the Promenade.
There are two diners as well -- Clarks which is next to Tazza, and Christine's on Montague btw. Hicks and Columbia. Neither is great, but both are good enough.