You could try Guadalcanal Diary, Richard Tregaskis; With the Old Breed, E.B. Sledge; On Valor's Side, Grady Gallant (what a name), and Helmet for My Pillow, Robert Leckie. These are well-regarded classics of war literature. (Gallant also wrote a second memoir, The Friendly Dead.) Tregaskis was a war correspondent, but he got rained on just like everyone else. The others are Marines, and deal with Guadalcanal and other campaigns.
You should also check out Ernie Pyle's books -- Pyle was a correspondent in Africa, Europe and the Pacific, and was killed during the Okinawa campaign.
A personal favorite of mine was the wartime memoir of the destroyer USS Grayson (DD435) written by her skipper, Frederick Jackson Bell. The destroyer's name and that of many other ships was censored in the wartime edition for security purposes, but you could tell it was Grayson because they didn't censor the hull number in her photograph.
It's a charming book about life on a destroyer -- and it is available on Amazon Kindle as Condition Red: Destroyer Action in the South Pacific. I wonder if the
Kindle edition has the crew list appendix with the creepily-historic "n" after the names of the African-American crew members. (Navy ships had mostly black stewards and kitchen staffs, but not combat crew) Another good destroyer read is Brave Ship, Brave Men, which details the story of the short life of DM-34, the USS Aaron Ward. Second ship of that name to fight in WW 2. The book is mostly about her harrowing experiences on radar picket duty off Okinawa, 3 May 1945, during which she was struck by multiple kamikazes. Although not strictly-speaking first-person (it is drawn from the stories of survivors), it is one of the most gripping and intense accounts of naval action you'll ever read.
Of course you want to read Studs Terkel's The Good War, a landmark of oral history.
And of course Company Commander by Charles B. MacDonald, another all-time classic.
Some all-time great war novels are really autobiographies: Mailer's Naked and the Dead and Jone's From Here to Eternity being the standouts here. Slaughterhouse-Five by Kurt Vonnegut also falls into this category, with its emphasis on the firebombing of Dresden which he witnessed as a POW.
You specify US accounts, so I won't mention the abundant literature from the other participants. But you should check out the German author Willi Heinrich (Cross of Iron and a number of other novels) if you'd like to get a viewpoint from "The other side of the mountain."
There are abundant web resources for first-person accounts of WW 2. It's impossible to even scratch the surface.
-- Mal