How I'd like to see a Flash movie
Given the right writers and director, something special could be made, hell just look at the Director's Cut of Daredevil. I've looked at the ten year Superman-related series by Al Gough and Miles Miller as a solid example of how visually amazing 'super-speed running' can look and that was always on a modest or low TV budget, so the technology exists to make Flash's key power look fantastic on a theatrical scope. Stay true to the basics of the character, be a charming and at times humorous story, but also don't venture into an all-out Green Hornet type comedy like Green Lantern did.
One thing I would stick true to is the metaphorical family vibe of the Flash franchise, make those in Barry's life that aren't even his blood more family than his own father. Say his father hasn't even been a father to him since his mother was killed and he hasn't kept touch with his brother since a child, therefore he's got other people in his life like his best friend at work, his girlfriend Iris West's nephew (Wally!), the mysterious Obi-Wan type old man Jay Garrick, all of them can become his family over the course of the origin movie. Regarding a foe for Flash, it's hard to select an intimidating one (just look at the JLU ep highlighting a Flash museum, they're all practically buddies of his!), but I think the most logical choice would be Mirror Master (Grodd's too out there, Captain Cold too cheesy) with a bigger one behind the scenes pulling the strings, say Vandal Savage.
One true struggle I'd make is Barry's choice rather to reveal his identity to the world or not, with his choice of wearing a mask clearly giving off suspicion that he has a normal life amongst the people he speeds around to protect. This is where Jay can come in, a retired super hero in his own right whose open identity antics as the original Flash have been all but forgotten or covered up, giving him a good example of what he feels he should do. Then there's Wally, a mid-teens 'our eyes' perspective who can eventually learn Barry's true identity and while not yet becoming a Flash in his own right, can help preserve that secret while Barry can be the kinda older brother to him his own never was. Barry's pal in the forensics department at the police station, let's just call him Jack, can serve the function as oblivious and helpful investigative best friend that like Iris, tempts Barry's secret reveal.
No romantic angst or triangle crap in this story regarding Barry's relationship with Iris, no 'leaving her' at the end of the movie or prior to its events, they're together and true loves to the end. The only splinter that isn't even really a dent in their feelings come via Flash's secret, but even then I'd at least let Iris 'secretly' know in her own right by the movie's end that Barry is the Flash. Sorta the same logic with how Carol finds out Hal's in Green Lantern, but more on the touching and less comedic side similar to how MJ nearly recognizes Peter's kiss at the end of Spiderman or how Lois recognizes her Man of Steel's kiss as Clark's at the end of that series' Season 9. It's a classy way to do it that isn't too cliche quite yet, I say go for it.
One real heroic struggle I'd throw Barry would be in one of his confrontations with Mirror Master, Flash would get thrown into the 'mirror world' where he'd need to recognize the way back to find the right world. This would establish there are many alternate realities and one other he visits by accident would be one where his mother was never killed, he's never met Iris, Wally's a drug-addicted teenager, and Mirror Master is his only hope of giving the mirror world one more shot. To make it back in, Barry must master his most troublesome latent power, to vibrate through molecules and glimpse the speed force (something spoken of by Jay) itself. He finds himself back in the mirror world with the worse bloody nose he's ever had, then gets back to the real world and stops his Mirror Master once and for all.
End the movie with a beautiful family dinner where Barry, Iris, Wally, Jack, even Jay are all sitting together (this being the scene where it's clear Iris knows the secret in her own 'secret' way), only for a knock on the door. We don't know if it's Barry's father or brother, but he opens the door and simply says "I guess it wouldn't be a family without... Come on in" Then the movie ends. After the end-credits, atop a roof above Barry's apartment at night, Jay meets with a caped and helmet-donning figure in the shadows.
Jay: "So Doc, is the boy working up to be an ideal successor?"
Doctor Fate: "The fates of life have many paths, especially for this boy. Unlike our Golden Age, his Silver Age will be one undeterred by hypocrisy and inner evils."
Jay: "As long as his future is bright..."
Doctor Fate: "I suspect the end of his journey will be more important than any of ours, Barry Allen may very well be more than any of us could imagine."
END.
Superman & The [Red-Blue] Blur = The Man of Steel