I spent the last 5 years approving expense accounts as well as submitting them.
I've never rejected a single item nor have I had one rejected myself by my boss. I've asked a question or two, as has he, but it's always just to find out what the expense is (our expenses are approved and the receipts come later).
I've always instructed my employees that when they travel for the company, they should not feel they need to be out of pocket any more than if they were home. I gave lots of examples -- Starbucks in the afternoon, snacks between meals, if needed, whatever. We also didn't blink on someone who wanted to drink a few beers with dinner or even went out for a few beers with teammates or clients *before* dinner. Even alone.
This whole "not eating the hotel free breakfast" wouldn't even hit my radar cause I don't sit and wonder what kind of breakfast the hotel provides. I've stayed in hotels where the options were cereal and a wafflemaker with coffee-flavored water and I would never expect someone else to eat that in lieu of a nice breakfast.
Truth of the matter is this -- when people are trusted and you demonstrate to them that you trust them and that you're not treating them like children, they are better employees. They will go an extra mile for you and the company and they will, left to their own devices, do the right thing.
There's never been a single instance with my team where I thought someone was trying to take advantage of me or the company.
Others' mileage may vary.