My idea for a Flash television series has always been an extension of my movie idea, or should I say, my idea for a movie has always come from my television idea, just wrapped into a two hour movie.
My television series would deal with the Flash Legacy, the speed force, everything. The show would open with Barry Allen as The Flash, and a powerless Wally West, which is unlike the comics, but I have a reason behind it. I would incorporate Jay Garrick into the series, adpating the comic storyline that originally featured Jay Garrick being a comic book character that Barry Allen based the Flash off of. Here, Jay would have been The Flash, having gained his powers from inhaling fumes, and due to the nature of his costume, having been a publicly known hero, which would have worked in against him in the long run. I would feature Garrick stripped of his powers, either due to villians acting against him or for health concerns, maybe introducing a storyline about the fumes being a bad way to gain the speed powers. Anyway, once Barry gained his powers through alternate means, he searched out Garrick, who helped him develop a secret identity and mentored him in being a superhero.
Anyway, Barry Allen is the beloved Flash in the pilot, and story short, dies. Before dying, the bond between Barry and Wally, as well as Iris and Wally, is firmly established, and unknown to Wally, Barry would have already made plans with Jay to recreate the accident for Wally in the event that something happened to Barry, because the world would still need a Flash. As you can guess, when Barry, dies, Jay does indeed recreate the accident, giving Wally the speed powers, and trains him to become the new Flash in the shadow of perhaps the greatest hero of all time.
Wally trying to live up to the standard Barry set provides enough storyline alone, and I would add in flashbacks to Barry as The Flash, and show Six Feet Under like scenes that would show Wally, in his head, talking to Barry about what he should or should not do, or something h has done. This is where I got the idea for Peter Krause to play an older Barry Allen. As supporting characters, you have Jay and Iris, as well as the relationship between Wally and Tina McGee so you could gradually bring along Linda Park, who would be a regular from the get go. A combination of the Reverse Flash characters would be the season one villian, which would place off of Wally trying to replace Barry well in my opinion. Throw in some original characters, and it could be nice. Storylines dealing with the speed force, Flash Legacy, the Flash museum, it would all work within the context of th show.
I know I have altered some comic stuff, but I think this all could go together nicely and create atleast a cult hit television series when its all said and done.