Ideas for Flash 2 & 3:
I'd have the Rogues in the movies eventually. Part 2 would feature Captain Cold and the Reverse Flash with an introduction (more of a cameo) to a very young Wally West (10?). I'd also maybe put Jay Garrick in there as a Flash from another dimension, Barry will discover his ability to slip between universes, and yes, also time travel in this one. He will fight Cold at the beginning of the film, and maybe he shows up again at the very end with a plan to bring all the Rogues together (to take on Barry in the third).
The third film (hopefully they will have done a JLA film or two by then, ideally I'd want to have Flash sacrifice himself saving the world in JLA, but just to be safe I'll keep the plans limited only to the individual franchise) will have Barry taking on the Rogues with the help of Kid Flash (maybe Jay stops over to lend a hand), and also the intergalactic threat of the ANTI MONITOR. Barry sacrifices himself to save the universe, running 1000s of times faster than the speed of light, so fast that he moves backwards through all of time itself and he "becomes" a "human thunderbolt", i.e., the lightning that hit himself granting himself superpowers. However, his consciousness resides in the speed force, and it is revealed that he created/generated the speed force the night of the "accident", and the more he runs the more energy he generates, he's its engine, and it "overloads" and hits someone else with his sense of justice similar to his (Wally) to keep itself going. (There is also a "negative" speed force that Thawne will create) Wally will discover all this in future movies, mind you, and there will be a way to bring Barry back eventually, but the big thing at the end of my original Flash trilogy will be that Barry saves the world "becoming" the lightning bolt that hit himself, and Wally becomes the new Flash at the end. Last scene in the movie would be Wally holding The Flash ring/suit. And I had that idea before TDKR haha. But that's the plan.
In the next eventual movie, Jay sticks around to "mentor" Wally a little until he gets on his own. And whatever they decide to do after the original trilogy, whenever they do it, whether it's a tv series or a new trilogy, the story is set up to feature Wally West as The Flash with the original trilogy as the back story. And then that trilogy (the new one) could end with Barry's return and them all living happily ever after. Well, actually, before the REAL Barry returns, preferably in the second film of the new Flash trilogy (5th Flash film), the time travelling Reverse Flash aka Professor Thawne will return and claim himself as Barry Allen and believe that he IS Barry Allen for the bulk of the film, and he will go around doing evil things. This movie will be based on the greatest Wally West story ever written, and that is the Return or Barry Allen arc. At the end Wally will have made peace with the "ghost" of Barry Allen and finally come into his own as The Flash. In the next film, Barry Allen will actually return, and they will both patrol the cities as a family of Flashes. This story could be based off of Flash: Rebirth, where Thawne revives Barry Allen and all that stuff about the "negative" speed force is revealed. Good ****.
^^ That's what I'd do personally. There's just such much potential there ya know?