Shawtycat do you own the book "Blue Plate Special- The American Diner Cookbook" by Elizabeth McKeon and Linda Everett? I've made several recipes from this book and REALLY really like it!
It has many fountain drinks...too many to list, parfaits, malts and fizzes which of course... I'd like to taste all of those too.
Their desserts are as follows:
Applesauce cake, apple-raisin rum cake, apple spice cake, raw apple cake, banana cake, chocolate cake, black forest, carrot, lemon, orange, sour cream, mississippi mud, pineapple upside down, angel food, velveteen, strawberry, pound, chocolate brownies, diner cheesecakes, black & white cheesecake.
Then they have a section on pies: strawberry cream cheese pie, apple ppie, banana cream pie, caramela pie, chocolate chiffon pie, choc, custard pie, choc, cream pie, choc. marshmellow pie, key lime pie, lemon meringue, lemon chiffon, fresh peach, pecan, peach upside down, peanut butter, pumpkin, raisin, raspberry, custard.
Going into cobbler: apple, peach, apple pan dowdy, apple crisp.
Apple studel, blueberry strata, blackberry slump, jello, choc. pudding, lemon pudding, rice pud., custard, tapioca, chocolate banana tapioca.
It kind of looks like diner desserts are very similar to Amish recipes...lots of overlaping with pies, cake and cobblers. I also own alot of older baking books from name brands product and companies (like Hersheys, Jello, Pillsbury, Betty Crocker). There's quite a rang of desserts to work from and it's really a fun topic.
This book also contains some diner slang phrases which are amusing....anyway I high reccomend this book.
Looking at your menu....what I might do.....loose the danish and make donuts (very pop. and authentic)...I'd go with a chocolate peanut butter pie (always a big seller) on gram. crust. Maybe some layered jello paraits in float glasses just for looks in your case (provided you have a show case)...maybe switch out some fruit pies for slumps and crisps because crisps and such are far easier to make, hold and serve in different qanitities. Also they love that hot fruit crisp ala mode.....hey what about fudge wrapped in wax paper, it holds well and is true to that time period...
etc.... I have no limits of opinions and ideas when your talking desserts.......