My sense is that you need to find a large RV show not sponsored by a dealer. You can walk through numerous floor plans, pick up info on specs, and determine if a unit can be custom ordered. Some of things you indicated, like the toilet and generator, should be easy. Others, like a large kitchen, need to be further defined by you, perhaps in square feet.
Our motorhome does not have slides. A number of people on the forums have reported issues with them, but there are many others who have had no problems and swear by them. So, its a personal choice. I suggest you don't rule them out at this point unless you *know* you don't want them. They will provide more room, and can be had to increase the kitchen area.
Good luck.