I used to volunteer for a small office that required a lot of traveling to conferences and such. Since the office was extremely small (about 10 people), our financial officer was able to review all the expenses. The travel policy was pretty simple- find the cheapest flights possible and include reciepts for anything you want to be reimbursed for. Limits were set for meals, so if you went over that, it came out of your own pocket.

Overall, the policy worked really well, but mainly because the office was so small.