I'm looking for an app that would allow me to show pictures to clients for the sales consultation. It would be great if I could arrange the pictures around to give clients ideas of different arrangements. Thanks for your suggestions!

Not sure if this is what you want but check this thread:
Pro photographer - just joined the community

If you sync your iPhone/iPad to iTunes, you can sync photos from a folder/subfolders in your computer to your device.

The option is under "Photos".

Then you can browse all your synched photos in the Photo app.