Ateres Chaya is convenient for Flatbush/Boro Park. Mr. Jacobowitz is a mentch and will work with you!!!
With halls in the basement, check out walking down the stairs for safety reasons and make sure they have a permit for a hall downstairs.
Be wary of halls that charge extra for each additional chair they put out or for unionized halls that let you sit only at the table with number on your card, even if it is an error and the table is a children’s table. I had that happen to me in a posh hall and i was ready to leave rather than sit with such as 3-8 year olds. When the person who invited us saw us trying to leave, they literally had to fight for something they were paying for ,big money a bigh $100,000 for the night!