When I was with a very large US based IT company, they used Concur for the travel bookings and expenses, and it worked very well. The travel booking portal presented the flights and pricing based on the travel policy, but you could select other flights and provide the reasons e.g. I had to take the first flight of the day to make meeting at 9pm. Depending on your role, you had different options for travel e.g. Sales, BD, or Project (had to provide a Job Code/WBS).
Our corporate AMEX cards were tied into the portal too. After I had charged something to the card, the next day I could see it in the portal, add in the details, upload a photo of the receipt, and that was the last I would hear of it, as work paid that item. You were allowed to put part or whole personal costs onto the card, and pay them separately. For example, if I bought food and extras at the supermarket, I would claim the part related to work.