The nicest Travel Policy I ever had was at Kwik-Fit (but then, Sir Tom Farmer was unique as a "business brain") where Travel/Accommodation allowances were published in a table. (Of course, Kwik-Fit being largely British, travel was mostly UK) I can't remember the exact allowances but the essence of Sir Tom's policy was that you had an agreed allowance and whatever you saved the company was shared 50/50 between the company and the employee! So, although you could stay in a "Thistle" hotel or equivalent, if you wanted to stay in a B&B and dine on MacDonalds, you could boost your earnings!
(So, if your allowance was £60 and you found a B&B for £30, you would earn a bonus of £15 - less tax of course!)
The policy on Company Car fuel was strict and one or two landed themselves in hot water as a result - any free tokens had to be returned to Head Office for charity. "I don't want you bu66ers driving 20 miles out of your way because of the free glasses!" quoth Sir Tom! He would probably have had the same thing to say about airlines, mileage and tier points!!!
......the policy was fair and Kwik-Fit was fair. Sir Tom's philosophy of "Treat the staff right and they won't fiddle you!" seems to have been well-founded, reading the threads here!!!