It'd be nice to see some books on American history that avoided the Civil War, Revolutionary War and the Wild West, or at least covered them without buying into too many tropes and cliches.
I think that's the problem with both the Civil War and Revolutionary War. Everybody thinks it's cliched. If you are a student of history and know what you are writing (and/or reading), then it shouldn't be cliched. The real issue at hand is preference. You either like that era or you don't. There are certain cultural markers that have to be tackled in a Civil War novel. Some might call those cliched but they're not.
I think the Civil War era has been so maligned, it may be impossible to redeem it. What a lot of people take for granted as true really wasn't. Like all southerners owned slaves and signed up to fight for slavery. Um, no. I think something like 2% of the southern population owned huge plantations with with hundreds of slaves. I believe I read once that the overwhelming majority of slaveholders only owned a handful of slaves. My own family were dirt poor farmers with no slaves before the Civil War, but they fought for the south because ultimately, they didn't want to be told what they could and could not do. Just like now...we don't like people coming down and telling us what to do.
So why should anyone avoid the era just because some people have a "Gone with the Wind" complex, which for all intents and purposes, was not the most historically accurate novel out there? If you break it down past what some consider "cliched," it is a fascinating time period. The entire course of our nation was changed because of a war. The same could be said of the American Revolution. Of course both periods are popular--there is endless fodder to be fictionalized! There are so many different POVs.
Personally, I'm sick to death of the Tudor era. How many novels about Anne Boleyn can the market bear? Apparently a lot. I don't understand it, but that doesn't mean new offerings are not worth while. I used to love that era, I will still occasionally read books from that era, but I wish the market would move on. But it won't because people buy books from that era. It's not cliched, it's preference. The same could be said of the Marie Antoinette/French Revolution. That's quickly becoming the new hot topic in historical fiction, IMO. How long will it take for people to consider it cliched?
But with that being said... As the Hip-Hop-a-potamus, there seems to be an upswing in American historicals lately. Ciji Ware, Megan Chance, and Daisy Goodwin are publishing late 19th century historicals that are either wholly set in the US or feature a part of the story in the US. Mary Sharratt, Kathleen Kent, and Sally Gunning are putting out novels set in the early days of the American colonies or during the American Revolution. Nevertheless, some agents are leary of taking on American historicals because they think the market is not receptive to them right now. It will change. Change is constant, after all.