So, to help out, a few ideas for collections that would get the hearts of fans of the CW's Flash show racing!
Flash Vs. Reverse-FlashSuperman-Flash races in Flash #175 and DC Comics Presents #1 and #2, and his appearances as a member of the Secret Society of Super-Villains in Secret Society of Super Villains #12-15 and Justice League of America #166-168 facing the Justice League of America, though only available in hardcover, so a softcover companion like Secret Society of Super Villains Volume 1 had would be nice).
Flash #139, Flash #147, Flash #153, Flash #165, Flash #186, Flash #225, Flash #233, Flash #237, Flash #281-283, Flash #323 and Flash #324, you'd collect the beginning to end of Eobard Thawne in 275 pages including covers, (well, more or less, missing a few one page appearances, and the results of his end in Flash #325), and have a book Flash TV show fans would like, as they could see Thawne's Silver Age life unfold!
Flash Team-UpsAtom in Brave and the Bold #53, Martian Manhunter in Brave and the Bold #56, the Doom Patrol in Brave and the Bold #65, and Spectre in Brave and the Bold #72. Flash also worked with Hawkman in Super-Team Family #3, and the New Gods in Super-Team Family #15.
Superman/Green Arrow team-ups could be collected), and Showcase #100 (which has Flash working with, well, everyone who premiered in Showcase, a title which introduced Barry Allen to the world as well!), which would get you over 240 pages with covers!
You even get a lot of action with Superman, Batman, Green Arrow Black Canary, and even Grodd and Captain Cold) all right round 300 pages.
Wally Settles As Flash
It took a while for Wally to get use to being the Flash, and he even wore the same outfit as Barry Allen did for a time.
Vixen and Rex the Wonder Dog, and then deals with Vandal Savage, all the while protecting his friends including Elongated Man, Tina McGee and Chunk. Throw in the epilogue of Flash #51 (with Flash helping the new Lady Flash and the Kapitalist Kouriers, written and drawn by the same team, but inked by Roy Richardson), and you'd have about 250 pages of super-speed fun!
Flash Vs. Demonic Rogues
Rogues' Gallery, whom had been assumed dead from their dealings with the demon, Neron, in Underworld Unleashed (and Argus, Jay Garrick and the Justice League of America guest-star to help with this!)...all in 230 pages, including covers (and, throw in Flash Annual #10 from 1997, to get the collection up to 283 pages...and see Wally fight Rainbow Raider, as well as a Pied Piper solo story...).