5 Questions Travelers Don't Ask Until It's Too Late

— -- Ever felt the thrill of having a really good coupon for a super discount on something you really, really wanted? Only to notice, too late, the darned thing expired?

I'm convinced procrastination is embedded in human DNA, and we all put things off. Unfortunately, there are sometimes penalties for procrastinating, especially when it comes to vacation planning. It could cost you, and big.

So please, don't be the person asking these questions when it's way too late.

1. Hey, boss, can I have next week off?

I've heard this tale of woe before: an assumption is made ("I'm sure no one else will want the first two weeks in July off"), tickets are purchased and only then is the vacation request sent through channels.

If the boss says no, you have two options and neither one is much good: Plead with a co-worker to swap (and you might be asked to trade precious time-off at Thanksgiving or Christmas), or change your reservations. If you change, brace yourself for the stiff change fee, $200 on American, Delta, United or US Airways. Wait, there is a third option: Pray you're flying Southwest, the only airline without a change fee.

2. Would it have been cheaper to travel a day or two earlier (or later)?

This is something to pay close attention to if you're traveling in spring or late August because flying one day earlier or later could save you 20 percent or more. Some quick examples.

Domestic flights: Many airfare sales are valid for travel through June 3. Watch some airlines hike prices for flights on the 4th. Look for another mini-hike in late June, but watch fares drop after the third week of August.

Europe flights: Most trans-Atlantic routes offer lower spring fares through May 12 or 13, but if you fly on the 14th, watch peak summer rates kick in. And don't fly Aug. 20 because we're seeing a drop in prices for fall starting the 21st.

3. I wonder what JetBlue would have charged? (Or Virgin America or Delta or…)

Here are the facts: You must compare airfares. Every time you shop for tickets. It's very simple: No single airline always has the cheapest fares. If you don't compare, you might get lucky and get the cheapest fare anyway, but there is no guarantee and it's just as likely you'll pay too much. Compare fares. It only takes seconds and could be worth hundreds.

4. Fees? What fees?

Airlines aren't out to trick you, but you're never going to see big, splashy neon signs on airline websites proclaiming, "Don't forget our $25 checked-bag fee!" Look for a small, discreet two-word phrase: "Optional fees." Click or tap and learn a lot, including whether there's a bag fee (Southwest has none) or whether the airline charges for all bags, including carry-ons (Allegiant, Frontier and Spirit do). Some airlines even charge for soft drinks and none provides free meals in coach. Look at the fees ahead of time to avoid an ambush.

5. Is my passport still valid?

An acquaintance who is forever jetting off someplace exotic recently scrambled for an appointment at a busy federal office to expedite a new passport. No, her passport had not expired but she was heading to a country that requires visitor passports be valid for several months even after the visitor returns home.

If this seems like a strange quirk, you should know that plenty of countries have passport regulations that seem a little quirky. For example, don't go to Italy or France if your passport expires within three months of your return or you won't get in. Russia and China require six months validity after your return, but Australia is happy as long as your passport is valid the day you enter. You won't know if you don't check, and the U.S. State Department's travel website is an excellent resource. Just don't wait until it's way too late to do anything about it.

The opinions expressed by Rick Seaney in this column are his alone and do not reflect the views of ABC News.