If you are going for Modern,

Mayhen Armory has listed on it's product page for scenery bits,
Patio railings
Concrete roof liners
2 pistol cases
Slanted ammo stand
Payment desk
Interior stairs
Sofa
Kitchen sink (yes, really!)
Fridge
TV
A/C
Rooftop air filter
Worktable
2 tool cabinets
Exterior ladders
Patio umbrella
Picnic table and benches
5 pick-up trucks
Store and Patio awnings
Store signs for Armoury and it's competitors
Billboards and blank store signs


Bits has a lot as well, which you picked up, but if you want to turn your Gas station inside into a functional unit grab Armory and put in one of the options for walls, and some of the "store" type stuff from it, may be a bit of a bash, but should be do able.

Bits: Downtown is basically more front flats to just give outsides, but you could using armory or possibly a kit bash (not sure if one exsists) make some insides for it.


Mayhem Industrial, has some insides (an office) as well as out side bits.

Rail is pretty much outside no real way to flesh out a inside of a building.

Mayhem PD, has a lot to flesh out the inside of a place.

Marina, more outside

If you want a little more Future Sci Fi, Mars Station, or First light, if more Horror/Zombie Shellendrak.

With the card stock you can make some of them "fully functional", just score the door hinge side, and cut the the lines for inside frame andyou got an opening door, same for window,, (thought just cut out the glass, sandwich a layer of transprencey or thin clear plastic, and you have a window. If you are using the Foam core, it might be a bit trickeyer, but the 110lb cardstock sandwiched with two layers (front side back side for a room building etc) are actually REALLY sturdy, and if you are worried about the support with foamcore, you might not need it (also goes a heck of a lot faster)... I'd say try one with out if you haven't and see if you like the difference.

But honestly i have to say you can get a lot of good info from the product page in question, they all list excatly what comes in the set, and many typically have a photo of all the items that can be made with that set.