These are the main problems I see with the Smackdown brand right now: staleness, an overreliance on the same few established guys, no interesting feuds or angles, and (this one's just my opinion) a recent shift away from in-ring quality and toward the Raw-styled "entertainment" aspect that just doesn't work as well on the B-show. I'll freely admit that I'm not too skilled as a writer, creator, etc., so most of my ideas will be influenced by ideas that came before me. But at least those ideas worked! So here goes.
1. Alberto Del Rio. WHC. Now.
The usual formula for new guys is building them up over a long period of time and then putting the belt on them. Well, like I said, I'm borrowing ideas that worked in the past. Here I'm looking at Sheamus' build over the last year. It was a shock when he got the #1 contendership, and an even bigger shock when he won the belt. Let's do that again! ADR has huge heat already, and he's proven tremendous ability in the ring and on the microphone. The best solution is to shake things up. The main-event picture since June has been Kane-Undertaker-Edge. Been there, done that. Lots of people will suggest moving people to Smackdown, but I think there's a better answer: shifting around the people they have. We can negotiate about Ziggler, Kofi, Swagger, etc., but for me the MUST is putting Del Rio in the main event. It would give the show some much-needed freshness and direction.
2. Move the Undertaker to Raw.
I have nothing against the Dead Man. I don't love him as much as most people, but I recognize how awesome he is. But it's pretty clear that he's a part-time worker at this point in his career. And for the few months at a time he's able to work, there seems to be some pressure to put him at the top of the card. I think this is detrimental to all the aforementioned young talent, as it takes a spot away from them when he's there and puts an unfair pressure on them to match his star power when he (frequently) isn't. I'd move him to Raw in exchange for an established Raw star, like Randy Orton maybe. It doesn't matter who (except it can't be Cena obv). Smackdown will always be the Undertaker's show as long as he's there, and he just can't meet that burden anymore. Let's move him along and give him a more fitting part-time role on a star-studded Raw roster. My only regret would be that we'd lose out on Del Rio/Taker, but after the Punk/Taker angle left me cold, I don't know that we're missing much.
3. Change some heel/face dynamics.
Right now, Smackdown is really heel-based. Kane, Cody Rhodes, Jack Swagger, Alberto Del Rio, Drew McIntyre, Dolph Ziggler, and (if he moves there, as well think he should) Wade Barrett. There are faces on the roster of course, but Kofi Kingston's the only one I see with any future. WWE needs to find a diamond in that pile of heels, someone they can build up with an eye toward turning them face and pushing them up. I'm not saying that they should turn face right now, but WWE needs to commit to them and start building their credibility and presence in the fans' minds. Maybe Swagger could pull off the goofy Kurt Angle-like face role, and he could get away with it by supplementing it with some solid, serious wrestling. I envision Alberto Del Rio as a monster heel in the near future. Cody Rhodes is a damn good heel (I hate to say it!) who is perfect for that role and that role only. They need the faces to go up against these good heels. My number 1 suggestion is Dolph Ziggler. God, I hate that name, but I think he could be a great face in the near-future. What they need to do is take the microphone out of his hands and let Vickie do ALL of the talking. Then, soon enough, he can get sick of her, break away from her, and the fans would connect with it.
It's tough to make specific roster suggestions with ever-changing rosters, but these are the 3 things I'd look to do first in order to get Smackdown through a creative lull.