Sometimes I'm a fly fisherman, sometimes I'm a fisherman with a fly rod. Bottom line is that I love to catch fish, and prefer to catch them on a fly rod. I can feel the fish a lot better on a fly rod, hand stripping in the line. It removes the machinery/gears from between me and the line and the fish. A fly rod has some real limitations on distance and type of presentation, but I'll take those for the feel of the fish.
Sometimes I'm a fly fisherman. What I have found to work best in the Brazos is a black woolybooger about 1.5" long. It is the "go to" fly. I also use crawfish and hellgramite imitators. I know an awful lot of people love clousers, but I've only been able to catch a few random fish on clousers. Not that they aren't good, they just don't seem to work well where I fish. On my big three selection, woolyboogers, crawfish, hellgramites - I've caught bass, catfish, crappie, bluegills, buffalo, carp, drum, gar, and a turtle. Depending on the species I'm after and/or the particular area I'm fishing I'll either fish them with various lengths and speeds of stripping-in, or deadfloat with the current. These flys work well in either case.
Sometimes I'm a fisherman with a fly rod. I've fished with live minnows and tore up some serious fish, but not often as it is real hard to keep a minnow alive and on the hook using a fly casting technique. I use small soft plastic about as much as I do flys. I have two particular favorites, a 1" chartreuse gulp minnow, and a 3" soft plastic hellgramite. In both cases I tie on a No. 8 (smallish) hook and run the hook tip through the head of the bait, up the shank a bit and then out of the bait, then turn the hook and bury it back in the body of the bait. I do that in a way that lets the bait hang straight. This accomplishes two things, one is that it stays on the hook better when being whipped around in the air, and two is that it is nearly weedless. I push the point of the hook just to the surface of the bait. I've not noticed many missed hookups this way either.
The gulp minnow catches bluegills like crazy, small bass occasionally, big catfish a lot more than you'd think, the occasional buffalo and carp, and a pretty good number of drum. It doesn't catch large bass though. For large bass I used the 3" hellgramite, toss it into cover, and strip it back slowly. Used in a dead drift it also catches quite a few catfish, buffalo and drum. It will pick up the occasional large bluegill. Once in a while a bass that is out in open water, but that's not common.
I have some larger gulp minnows on order that I want to try on large bass in/near cover. Maybe they'll work, maybe they won't, eventually I'll know. I have also used 4" plastic worms, to some small success, again these are hard to cast and without adding a weight they sink very slowly. I'm going to try them again when the river goes down in a couple of months and get a better test base. I have a plastic frog, made for fly fishing, that I'll try out some day when I remember to take it with me. I used to have great luck with those when using a spinning rod so don't see why it wouldn't work.
If you pair this information up with the information on where to find river fish in my previous post, it might give you some ideas to try on your next Brazos river fishing trip.
Hope it helps. I know these flys/lures have provided me with some incredible fishing days.