Flatiron area - fun environment/good food - need help!
Describe what you mean by fun?
If you just mean a nice casual environment with really tasty food I love Giorgio's of Gramercy. Went there with my parents and I think this is a great restaurant for that type of dinner.
Maialino is also a great choice with wonderful Italian cuisine. Depending upon what you order you ca get out of there for $30-$50 pp.
If you want something a little more young, hip, loud and like Mexican food, Dos Caminos is a chain but is a solid choice for a good meal.