Find an online resource
Ranchseeker.com provides a listing of various national and international dude and guest ranch organizations, as well as state associations for Colorado, Idaho, Arizona, Montana, and Wyoming. It also describes the strict criteria required for membership. The Dude Rancher's Association site is helpful for both potential guests and those in the industry.

Another excellent site is Top 50 Ranches, which is "dedicated to showcasing some of the most breathtaking, authentic, and luxurious [international] ranch destinations." It also allows you to input dates, destination, and other info, highlights special-interest packages, and offers helpful articles and tips, such as what clothes to pack. American Cowboy's website has archived features on specific properties, as well as their picks for the best guest ranches, and Writing Horseback has similar content.

Authenticity factor
There's are all kinds of guest ranches out there, from the hokey, git-along-lil'-doggies, tenderfoot tourist mills (this is just a personal quirk, but I tend to think of these places as "dude," rather than guest ranches, although that's not necessarily true).

Some ranches are luxury properties (and may in fact be members of boutique hotel or high-end property organizations such as Relais & Chateaux), while others are very family-oriented, with rustic cabins. Many are working ranches, raising cattle or breeding horses. I strongly recommend the latter, for the most authentic, rewarding experience.

Plan ahead
Guest ranches often book up to a year or more in advance. Plan accordingly.

How long do you plan to stay?
Most guest ranches offer a standard week-long program, says the Colorado Dude & Guest Ranch Association (CDGRA). To get the most out of your visit, you'll really need that amount of time. Some ranches do, however, offer weekend packages.

Ranch capacity
Depending upon where you stay, you might find yourself in the company of only a handful of other people or a hundred. If you're looking for a quiet or kid-free holiday, be sure to take capacity into account during your research.

Accommodations
Are you looking for luxury or a rustic, refurbished historic cabin? Main house or separate building? Full-on Old West decor, or something a bit more modern or genteel? Mountains or desert? Tipi or luxury safari tent?

Dining
Whatever your preference, you'll find it: Family-style, communal, formal, menu options or no, traditional Western cuisine, kid's menus, cookouts. Some properties, such as Colorado's Dunton Hot Springs and The Home Ranch, or Montana's The Resort at Paws Up are justly famous for their food, made with locally-sourced ingredients. Policies differ on alcohol, as well: be sure to ask whether it's included, or if you need to BYO.

When to go
The best thing about guest ranches is that most operate year-round. It's hard to beat summer in the Rockies, but you may want to consider visiting in the early fall, when the aspens are changing color. Winter allows you to ride horseback in the snow and engage in traditional winter sports, or you can head to parts of the Southwest or California where the climate is mild. Depending upon where you want to go, spring is the only time I'd suggest you think twice about, because "mud season" can be a logistical pain, and blizzards well into April aren't uncommon.

Activities and special packages
From traditional wrangling work--gathering cattle, roping, and caring for livestock--a ranch vacation revolves around horses and riding. If horses aren't your thing, this is the wrong type of vacation for you. That said, you don't have to ride, but you'd be missing out on a key part of the ranch experience. But there are all manner of outdoor activities offered by ranches. If paddling is your primary interest, look for a ranch on or near a river known for its whitewater. Ditto fly-fishing.

Many ranches offer specialty packages; Central California's Alisal Ranch, for example, hosts a four-day "BBQ Bootcamp" where guests learn how to master the grill from local experts, and enjoy a traditional Santa Maria-style barbecue.

Kid/teen programs
Most ranches are very family-oriented, and I can't think of a better--or healthier--vacation for kids. Be aware that every ranch has a different age policy, and not all offer kid's programs or babysitting. You'll also want to check on minimum age requirements for independent riding.

Level of horsemanship ranch caters to/Can you bring your own horse?
It may sound counter-intuitive to bring your own horse, but if you're an experienced rider, you may have a more fulfilling holiday and equestrian experience on your own mount (be sure to get referrals, first, to ensure your animal's health and safety).

Some ranches hold horsemanship clinics, which are as much about educating the animal as the rider. If you're just planning to pleasure ride but are an experienced equestrian, there are many ranches that breed and train their own animals and emphasize natural horsemanship and the cowboy way of life. Regardless of your skill level, you should always ask detailed questions about instruction, safety policies, how the ranch goes about pairing horses and riders, and their horsemanship philosophy. A poorly-trained mount or injury can really take the fun out of your holiday.

Handicap accessibility
Not all properties have it. Do note that some ranches offer riding programs for those with disabilities.

Phone, wifi, and internet access
Many ranches seek to provide guests with a complete escape from the stresses of modern life. If you can't live without your cell or computer, rest assured there's a property that can accommodate your needs.

Pack appropriately
A good ranch will always provide you with a packing list, but you can definitely leave your fancy duds at home. If you don't own a pair of riding boots or other heavy-duty shoe with a heel, get some (you can find an inexpensive used pair at a consignment or vintage store). These are essential for safe horseback riding, so your foot doesn't get hung up in a stirrup.

Proximity to a major medical faciilty
If this is a concern for you, definitely bring it up in your initial conversation. Many ranches are located in isolated rural areas.

Cancellation policies
Ask what they are.