The Travel Expenses Reimbursement Policy
(http://wiki.documentfoundation.org/TDF/Policies/Travel) appears to
say that if one chooses not to fly the cheapest way, or chooses to
stay at an expensive hotel, then no reimbursement at all will be
allowed.
I would think that the policy should say something like "only the cost
of low-cost economy airfare will be reimbursed; if travellers choose a
more expensive fare, they will be responsible for the difference in
cost" and similar for the cost of accommodation.
--Jean