Time for a little disagreement!
On size! Byron has stated to many folks on many occassions that I recal, whether being in the shop or on the board. In fishing these past 5 or 6 years, on and off, in the park I've come to notice that on certain days, specifically the spring and summer, size normally isn't an issue!
Now consider that a vast majority of my time fishing is knee deep in a tailwater, I don't fish the smokies as often as I should. I will say that fishing a tailwater is a whole nother animal!!! Size is a definate, color is next, and shape can ruin your day! I've run into that problem many many times on a tailwater.
As far as the smokies are concerned, get close on the size, don't worry to much about the shape, and definately pick the right colors!!!!
I've never had any real success with the weenie...but I'll give you a great fly for brookies with some good overhanging tree's in the smokies...It's a Serendipity....It's a simple tie too! I would use a TMC5262 in about a size 14 maybe 16, brown thread, amber wire (SM), and then use some elk hair for the head.....Hook in vice, catch in your wire, tie to bend, build thread base, whip, wrap evenly upshank with wire, whip, tie in clump of elk (on top), whip twice, then cut the elk hair so that it hangs over about 1/4 of an inch from where you tied the hair in at....It is a killer pattern that duplicates a brown inch worm! I've personally seen brookies come from about 4' away and slam that fly the second it hit the water, it was some of the fastest fishing you had ever seen!
Now as for other patterns I'd reccoment....Spotlight yellow sally (Umpqua), yellow "rabbit dubbed" parachute 14's and 16's, para adams 12,14,16, Bufus slow water sally 14 and 16, bwo's 16 through 22's, madam x sulphur and adams 14 and 16, terrestrials...the power of the ant folks!, and of course one rediculously sized goldne stone fly...that is one hatch that makes me angry! I never have one in the box when needed!
Those in your fly box, should land you fish all summer long in the smokies!
Oh, and a Doc's cork 14, 16, and a yellow humphy 14 16