The scopes is what will kill you as far as capacity goes then followed close by the AR style rifles especially if you have the magazine in them. All my high powered rifles except one has 50mm objective lenses and they take up a lot of real estate. I honestly believe the way safe manufacturers get the gun capacity claim is buy using old single shot .410 shotguns. Even my rimfires fit fairly close together and only two of those are scoped. With your collection and what you're anticipating on getting especially with all the scoped rifles, I wouldn't go any smaller than a 39 gun capacity safe. If you have the money and more importantly, if you have the room, I'd pick a bigger safe. I wouldn't have been able to get a bigger one for where I was putting it but now I'm having to start contemplating where another one is going to go.
I bought the Hollon Republic 39 gun safe and I probably have room for 3-4 more long guns. I took out the small shelves to give me three bays for my long guns and you're correct, most safes are designed this way. I did add the middle shelf that my handguns are on as mine only came with one large shelf which is my top shelf you see. All shelves should be adjustable giving you some flexibility. I will say this, I wish I would have gone with a taller safe. As you can see in the pictures, I don't have much room on the top shelf due to a couple of my shotguns having long barrels. One barrel is a 32" 12 gauge magnum and the other is a 30" 10 gauge. This is the main reason I had to build a shelf to hold my handguns.
These pictures will hopefully give you an idea of how well a safe accomodates real world guns with scopes. I probably could pack them in a little tighter but then I'd risk safe dings. Worst case scenario, I could put the guns in padded cases (not gun socks) and remove the notched barrel shelf and really pack the long guns in tight. But then it wouldn't be as much fun when I open the safe door
!
Here's the safe I have with it's dimensions and I'm very pleased with it:
http://www.hollonsafe.com/safes/RG-39.shtml
Here's the pics of how it looks.
[IMG]
[/IMG]
[IMG]
[/IMG]
[IMG]
[/IMG]