Most of the folks who frequent this site are in the middle Tennessee area. From Nashville, you can trout fish on the Caney and hit the big catfish on the Cumberland. That's what most folks on this forum are going to be most familiar with. We don't really have many creeks with trout in Middle TN though - there are a few marginal ones on the Plateau an hour and a half or so away, but for truly good creek fishing for wild trout, you need to head East up into the mountains.
There used to be a guide out of Clarksville named Joe Hall who was a master at finding the big blue cats. He put more cats in the 30-40 lb.-plus range over the rails than anyone else I know. I'm not 100% sure he's still guiding because I haven't talked to him in a couple years, but his number is listed here, along with some other guides you might look into:
http://www.tnoutdoorsmen.com/guides.htm
Richard Simms down in Chattanooga seems to do a great job at finding the catfish too. He shows up from time to time on this forum and always has a good report. His website is here:
http://www.sceniccityfishing.com/
He could probably help you with the crappie too.
For creek trout on the fly, you're probably going to be best off in East Tennessee.
You know, I'm starting to think of an itinerary that might work for you. You could start out up in Townsend and fly fish Abrams Creek, or maybe in Tellico Plains and fish the Tellico River area. Great Appalachian-style fly fishing in small creeks for wild trout in both places. Stay there for a few days, then head down to Chattanooga to catch a day fishing with Richard Simms for big catfish or maybe crappie and other species. That could work out well.
As an alternative, you could just base out of Nashville, fish the Caney Fork (not creek fishing by any means, but it's still good fly fishing for trout), and then fish the Cumberland for stripers or big blue cats, depending on where you go.
Tennessee has so many options you could fish here all your life and not hit them all.
bd