Piedmont has a great vacation plan, 1st year you get 5 days, 2nd-? 10 days, and sernior guys get 15 or 20 days.
You get 1 vacation slot per 5 day vacation period, either the 1st-15th or 16th-30th. You put your days you have on scheduled work days, and any other touching trips with those 5 days get dropped. For example if you have vacation the 1st-15th and have two 4 day trips during that period, you put 4 of your vacation days on the first 4 day, and the next four day trip drops as well (although you only get paid for the first day). Combine this with bidding the prior month so you have a few days off at the end of the month and it is easy to get 15-18+ days off in a row.
It is complicated at first but if you know how to work the system its great.