Great forum here. As a native Chattanoogan I thought I'd list a few locally-owned joints that I love. Some of these you've already sniffed out.
BBQ Pork: Porker's downtown
BBQ Ribs: Steve's Landing (Soddy Daisy, TN, way out but worth it...makes Sticky Fingers taste like Puppy Chow)
Breakfast: the Innside (downtown--looks ratty, be brave)
Burritos: Mojo Burrito in St. Elmo
Catfish: The River Inn on Suck Creek Road, not far from Merv's
Cheeseburgers: Merv's (on Morrison Springs Road, across the river but not far from Downtown--it's much safer than it looks...you will thank me!). If you want less of an adventure, try Armando's on Main Street
Chicken Wings: THIS is what you order at Sticky Fingers. Trust me--their Q is second rate, but they rule on this treat
Chinese: Formosa (Hixson area....in a strip mall, but don't let that throw you off)
Coffee: Greyfriar's (next to Lupi's), Chattz (closer to Porker's) or The Stone Cup (Coolidge Park area)
Deli: River Street Deli near Coolidge Park
Fine Dining: (just in case) St. John's in the Southside, across from Porker's
Fried Shrimp: Nikki's Restaurant
Hot Dogs: Griffin's is a unique experience...the original on Main Street is safe to visit, but there are now 5-6 locations around town
Irish Pub: Durty Nelly's near Coolidge Park
Italian: Tony's Pasta (Bluff view Art District)
Meat-n-3: Zarzour's Cafe, Rossville Ave. and make sure to order dessert. Also highly recommend the Southern Star located in the Freight Depot shopping area downtown (I'd avoid Bea's these days)
Mexican: Amigo's for the everyday, cheap Mexi-food experience, Tortilla Factory (downtown) for something a little more interesting (and also a great rooftop bar overlooking the Aquarium)
Pizza: Lupi's if downtown, Pisa Pizza if near Coolidge Park
Pastries: Rembrandt's Coffee House or River Street Deli
Sushi: Hiroshi's on the Southside or Sushi Nabe in Coolidge Park
Thai: Thai Smile near the Aquarium or Sweet Basil in the Eastgate area
NOW WHAT NOT TO DO:
DON'T be tempted by the Dinner Cruise on the riverboat....yecch
DON'T get your cheeseburgers at Cheeburger Cheeburger
DON'T go to Sekisui for sushi (near the Aquarium)
DON'T eat at any of the chains downtown...there are too many other choices!
Have fun while you visit our little town!