It's winter, the days for much of the country are more conducive to sitting inside than heading outdoors. So you're spending some time planning your summer vacation in the National Park System. How do you decide where to go?

There are some park units that don't require much thinking when it comes to deciding to visit them: Yellowstone National Park, Grand Canyon National Park, Great Smoky Mountains National Park, Yosemite National Park are all easy picks.

But beyond them, how do you decide where to go? Are you looking for particular vistas, whether they be mountainscapes or seascapes? Perhaps you want to have an active vacation, such as sea kayaking at one of the national seashores, lakeshores, or water-based parks. Or you could be in seach of a park that offers something for the entire family, for kids age 5 to grandparents in their 60s or 70s. Or maybe you just want a nice, clean cabin where you can relax with a book and maybe a short daily hike.

Part of the problem when it comes to deciding where to head in the National Park System is not knowing exactly what awaits you in the system. After all, there are 401 units. Are you aware of them all? If not, you might not know all that's out there that might be fun to sample.

So, how do you decide which unit to visit on your vacation? What goes into the equation for deciding?

And if you have an experience in mind, but are not sure where to go, relay it in a comment and we'll see if the Traveler braintrust can't make a suggestion or two.