Disclaimer: I'm not a TV writer. D&D are obviously better than me. Whatever I come up would be a lot worse than what they did and would have made for horrible television. The following is just for fun.
Season 4
I would have replaced the beetle-smashing speech with exposition about Tysha. Maybe include a "previously on GOT" flashback to the scene in season 1 when Tyrion tells Shae and Bronn about her. This was my attempt at writing some shitty dialogue for that scene after it first aired and people were saying, "but it would've been awkward to shoehorn Tysha in at that point."
With the Tysha exposition done, Tyrion's final confrontations with Jaime and Tywin could have played out much like the books. With some dialogue changes. Obviously Tyrion can't say "Lancel, Osmond Kettleblack and Moonboy for all I know" because two of those characters don't exist in the show. But something along the lines of Jaime being oblivious about Cersei.
A lot of people wanted LSH. I've come to terms with her being cut if Jon is going to resurrected. It makes his death and subsequent resurrection more powerful if we didn't just have a shocking resurrection in the previous season. But if she was going to be included, this is how I'd do it:
Make frequent references throughout the season to a "hooded woman" who is going around the Riverlands with her band of outlaws hanging Freys and Lannisters. I really liked that aspect of AFFC and I think it would work even better if the audience (non book readers) don't know who the "hooded woman" is. I don't think many people would suspect it's Cat. Not unless they've been spoiled. They may suspect it's someone with Stark sympathies, but not many would expect the woman who got her throat cut on camera to come back.
You can still have the Hound vs Brienne fight, I guess, since no-one really knows or cares who Biter is. But have Gendry come and save Brienne from him (which would also serve to put a lid on the "rowing Gendry" meme. Worth it just for that.) Only to then take her and Pod to meet the "hooded woman."
Next scene, this would be the final scene after Arya sets off for Braavos. Brienne and Pod have been brought before the "hooded woman." We still don't know who she is. We just see this hooded figure sitting in a dark corner. Brienne says, "who are you?" Thne Gendry of Thoros delivers the great line about how "she doesn't talk, but she remembers." Then she lifts her hood and it's Cat. Cut to black.
Season 5
It's a bit too early to say what I would change since the season isn't over yet and I don't where they are going with certain things. Some things that I don't particularly like now could turn out to be strokes of genius. But since I came up with a way to include LSH in season 4 I better continue on with how that would go:
First Brienne scene we see in season 5 is her being given a trial by LSH which ends in her and pod being hanged. Like in the books. No big cliffhanger this time though. Cut to black after she yells "sword."
I'd be happy then to leave it at that for a while until she meets up with Jaime again. Whether the audience would be satisfied with that, I don't know. There's also the issue of whether Jaime goes to Dorne or the Riverlands. As I said, maybe the Dorne thing turns out to be a stroke of genius. We'll wait and see.
I'd have also focused more on Cersei's paranoia about Tyrion. To do that you'd probably have to include the Volanqar part of the prophecy. I liked how crazy she sounded when she thought Tyrion was still hiding out in the Tower somewhere. I'd have liked to include the Tower of the Hand being burned after Tommen's wedding. But I'm not sure how much of the budget that would eat up.
I also would have also focused more on Tommen's wedding. It's become a meme that you don't invite GRRM to your wedding, or you don't have a wedding in Westeros, because there have been two major weddings now that have ended badly. So if you made Tommen's wedding more prominent, I think people would have expected something to bad to happen. Which is exactly how Cersei felt. It would capture her paranoia perfectly.