In the summer you want the clam shacks: Lenny and Joe's in Madison, Johnny Ad's in Old Saybrook, The Place in Guilford.
In autumn and winter try Darbar's (surprisingly good Indian food) in Branford, Siam Orchid in Branford, Marco's white pizza in Branford, and Taste of China in Clinton. To be honest I haven't eaten much in Guilford, but I found Cilantro's kind of expensive.
Good choices! I'll add a few more.
HIGH END: Cafe Routier (Westbrook) and Brasserie Pip and Gabrielles in Centerbrook (Essex), Darbar India (Branford),
MIDRANGE: Taste of China (Clinton), Bar Bouchon (Madison), Elisabeth's (Madison), Liv's Oyster Bar (Old Saybrook), Griswold Inn Wine Bar (Essex), Aqua (Clinton) maybe, SomSiam (Guilford),
SEAFOOD: Lenny and Joes Fish Tale (Westbrook and Madison), Lobster Landing (Clinton), Lenny's Indian Head (Branford).
Breakfast/Lunch: Christy's (Westbrook), Cafe Grounded (Guilford), Savvy Tea (Madison).
Outdoor: The Place (Guilford)
Liv's Oyster Bar
166 Main Street, Old Saybrook, CT 06475
152 Commerce St, Clinton, CT
46 Main Street, Ivoryton, CT 06442
20 Church St, Guilford, CT 06437
36 Main St, Essex, CT 06426
Fish Tale Restaurant
1301 Boston Post Rd, Madison, CT 06443
, Branford, CT 06405
8 Scotland Ave., Madison, CT 06443