Steve,
Being from Oklahoma, you've got to get into the Sandbass some time. It's one of life's real treats. Spring and Summer are the best times for a flyrod in my opinion although I've caught them every month of the year other ways. Fall can be good too. The Spring spawn is coming up. It's super. Many places they run up the creeks and rivers. We don't have much of that here in SW Okla. though. Around here they mostly spawn against windy banks. We don't have the good deep creeks here for them to run up. The Summer top water season is a gas too. They surface usually early and late in the day. You need a boat for this action on a lake although I have caught them from a jet ski (believe it or not). You need something you can race to them on before they go down. The Fall is also a good time to catch them shallow on windy points when they "feed up" on shad before Winter sets in. In the Winter they go deep and aren't too accessable to the flyrodder. Use Clousers and Deceivers the same size as the shad they're chasing. Blue and White, Chartruese and White or White are good. A 6 wt with sinking or integrated line is what I use. You can cut the wind better on the big lakes with a sinking line whereas the wind tends to catch a floating line. Good luck. If you do get into them, please post. I'd like to hear about it. If you're down this way look me up and if they're biting we'll take the bass boat out and give 'em a try.
Robert