I get reimbursed for actual expenses but have to use a company credit card (no points/miles for me from the charges). We don't have limits but if you are too extravagant your boss will let you know, and you are marked for life for extra scrutiny. They figure they are very flexible with reimbursements so if you go so far that they have to say something, you really must have abused it.
Personal mileage is the standard IRS rate.
And we never have to share hotel rooms, like some companies make you do.