Deciding how long to visit the Yucatán Peninsula  is one of your first decisions, and is ultimately a very personal one. The fact is, for some people, a week is all the time they want or need to enjoy the beach and see a few ruins; any more time and they’d start getting antsy. For others, a week is barely enough time to settle into the rhythm of a place, let alone do and see everything it has to offer.
Indeed, the Yucatán Peninsula has so much to offer, you’d have to stay for two months or more to really see it all. Of course, the length of any trip or vacation is most often determined by unrelated criteria, like how much time off work you have, how much you care to spend, when the kids have to start soccer camp, and so forth.
Ten to fourteen days is a reasonable amount of time to allow you to see a little of everything. Most people planning a trip through the Yucatán Peninsula (as opposed to just Cancún  and the Riviera Maya ) aren’t too keen on the big resorts, but you can still enjoy the beach—try the bungalows at Tulum , or the small hotels and B&Bs in Playa del Carmen , Akumal , Xpu-Há , or even Isla Holbox .
You’ll want at least five days in Mérida  and its surroundings to enjoy the countless cultural events the city has to offer, plus the Maya ruins and smaller colonial towns nearby. Add another 3–6 days for more remote destinations, like the Río Bec region  of southern Campeche, not to mention Tabasco  and Chiapas .
If you have a week or less, don’t try to see too much—you’ll just chew up a lot of time getting from place to place, and checking in and out of hotels. Rather, pick one or two places to really experience and enjoy—Mérida and Xpu-Há, say—and save the rest for your next trip.
No matter how much time you have, when planning your trip be sure to account for the time it takes to travel from one place to the next. Distances are not short in the Yucatán Peninsula, especially if you plan to visit Chiapas and Tabasco.
The best time to visit the Yucatán Peninsula has a lot to do with why you’re going and what you hope to see and do. Weather is a major consideration for any sort of trip. Cloudless skies are a priority if you plan on spending some or most of your visit on the beach. But you can have too much of a good thing—in the interior regions of the Yucatán Peninsula, a little rain or cloud cover can keep the temperature down and be a welcome relief.
Equally important is how much money you’re willing to spend, especially on accommodations, which can vary dramatically depending on the month and day you visit. If you’re on a tight budget, you may consider coming in the low season, but you’ll be taking a gamble on the weather.
Another consideration is that some activities can only be done during certain times of the year, like bird-watching or snorkeling with whale sharks.
Finally, be mindful of holiday and vacation periods, especially Christmas, spring break, July and August (when most of Europe is on vacation), and Semana Santa (Holy Week, the week before Easter and the main vacation period in Mexico). Prices can skyrocket, along with the number of tourists, both foreign and Mexican. Of course, if partying is high on your priority list, there is no better time to visit.
For most travelers, the best time to come to the Yucatán Peninsula is from mid-January until the beginning of May. This period does include spring break and Semana Santa (the best or worst time to come, depending on your point of view), but otherwise crowds are thinner and prices are lower compared with the Christmas and summer periods. Late November and early December is another pocket of relatively reliable weather, reasonable prices, and light visitation. But expect prices to jump on December 15, like clockwork.
Mérida , Campeche City , Cancún , Cozumel , and Playa del Carmen  all have modern stores, supermarkets, and malls, so you don’t have to be concerned about not being able to find the basics, and then some. However, prices on the coast can be exorbitant on items that shop owners know you can’t do without. Sunscreen, bug repellant, billed hats, and swimsuits are the most notable examples; if you think these items are pricey at home, the hotel gift shop will leave you floored (and broke!).
A few other items to remember when you’re packing: An extra set of contacts or glasses in case the ones you have get lost, broken, or washed away while swimming or snorkeling. Bring a supply of your preferred birth control, condoms, and feminine products—all are readily available in the region (and Mexico, in general), but you may have trouble finding the brand you prefer. Same goes for any prescription medications; many people, especially seniors, come to Mexico partly to take advantage of much lower prices on pharmaceuticals, but always bring enough for your whole trip in case what you’re looking for isn’t available. A travel clock is useful, too, because many hotels don’t have reliable wake-up call systems.
Finally, a good pair of shoes—or at least Teva-style sandals—are essential for visiting the archaeological zones. Never climb the ruins in flip-flops. The vast majority of accidents and injuries that occur at archaeological sites are from people slipping and falling, so you’ll want shoes that give you plenty of balance and traction.