I ride in an older Stubben Parzival dressage saddle for that reason: flatter seat, no rolls or blocks… I find it so much more comfortable!
I can’t quite make out the model of my Passier, but it has quite a large cutback and swept back points. Fits my big-shouldered percheron/morgan nicely (with a thin gel pad under it for a bit of extra squish since it’s hard and needs restuffed, but the person I trust to do the job isn’t back in town for a couple months) but also fit my old lease horse - a sharkfin withered OTTB with a cashel pad for even better squish for his old back. Without my large rear in it, the saddle doesn’t need the gel or cashel pad to fit properly, but being a heavier rider it’s only fair to give my horse the extra cushion until I can get it restuffed.
All that said, I’ve been riding in my western lately, and his other rider uses her Bates, so the Passier’s been sitting in the corner of he tack room with my AP Wintec Wide, waiting for a turn to be loved 
[QUOTE=joiedevie99;7206863]
I too prefer flat seated dressage saddles. Here are some you could try (some of these have flat and deep seat options, so you have to locate the right one): Butet, Passier, Schleese (older), Stubben, Frank Baines.[/QUOTE]
I had not heard of Butet saddles before, 'til I read your post, joiedevie99, but I just saw a beautiful one! Not the appearance I would have thought I would like at all, but I really love it:
http://www.google.com/imgres?imgurl=http://www.horseclicks.com/img/adphotos/210/394210_17-17-5-brown-butet-saumur-dressage-saddle_photo_1_img.jpg&imgrefurl=http://www.horseclicks.com/17-17-5-brown-butet-saumur-dressage-saddle/saddles/394210&h=422&w=563&sz=263&tbnid=75IudtRlziTapM:&tbnh=91&tbnw=121&zoom=1&usg=__3wHeRx3cTn8wPZGXqqZzKurGATI=&docid=Jd7MTbxbH0xLhM&sa=X&ei=zRZeUpO1CZTrkAe9w4GQAw&sqi=2&ved=0CD8Q9QEwBA
Haven’t read through all of this but I, too, prefer a flatter seat. Though I’ve been a long time Passier devotee, my trainer…well, not so much. After sitting in a ton of saddles (everything from Smith-Worthingtons & Wintecs (vomit) to the “air ride” DKs (OMG, yes, but wait it’s how much??), I ended up in a Prestige Optimax of all things. It has an open seat (their term, not mine) and a narrow twist (with a wide tree that fits my critter). It beautifully accommodates the lower back issues I have that other saddles seemed to exacerbate. While I’d love to have a DK for the cushy-ness, that was not in the budget and I’m quite happy w/my saddle. 
After this summer’s saddle purchasing adventure, I’m a big believer in the “ride in everything you can get your hands on” program of buying/shopping. Sometimes we are surprised by what works best for us. Good luck!!
I have a Tad Coffin Dressage saddle, flatter open style seat, would say it probably rides a bit more like a CC saddle (seat wise).
