Build ios and android app for travel agency

We need to develop a cool app for travel agency. The main features will be searching for flights/hotels and booking them, and making secure payment. Currently this is done through a website which connects to a database.
Other useful travel gadgets/tools should be added to the app to make it more useful and to get the clients to keep it on the their devices and use it frequently..
The attached image shows the main form we currently have on the website.

Attached business requirements for more details.