Simulator to run iOS apps on laptop?
I agree with Ryokuchasan: the only simulator I've heard of is the one bundled with the iOS development tools. This only works with apps you have the source code to because it compiles the iOS app for Intel to run in OS X (using the Simulator window as a screen).

It also has limited multi-touch capability, generally limited to pinch-to-zoom, so you likely won't be able to demo the majority of many apps. (Also, using the mouse to drive an iOS app can be awkward.)

If you want to do consumer testing with iOS apps, you need a physical device in the same room as the test user.