Anaheim, Calif. » The long awaited trip to Disneyland so many years ago was supposed to be special. The family saved for years for a dream vacation to the land of Mickey Mouse but the reality turned into a major disappointment.

The park was so crowded the family spent all day waiting in winding lines and managed to get on only five or six rides, a fact that Birmingham, Ala., author Bob Sehlinger, who made that trip, called "annoying beyond description."

After he returned home, Sehlinger decided to use his background in operations and research to see if he could collect visitor data and work out models to help families visiting Disneyland to avoid the pitfalls that ruined his dream vacation.

The result was a book called "The Unofficial Guide to Disneyland," an effort that spawned many other similar titles on popular destinations.

After recently taking two of my grandsons to Disneyland on a weekday during the second week of September where we were able to walk on to most rides and only the submarine ride had a lengthy line, I wondered if we had picked an optimal time of year to visit the happiest place on earth.

It turned out we had.

"Avoid the summer and holiday periods," recommended Sehlinger, who said the advice works for both Disneyland and Disney World in Florida. "The lowest crowds of the year can be found during the

period between Thanksgiving and the Christmas holiday and November leading up to Thanksgiving."

Other good times to visit are February, March and April before southern California schools begin having Disneyland days in the spring,

"Determine the best time by following the school calendar," said Sehlinger. "If school is out or there is a major holiday, it will be crowded. Since Disneyland is southern California's own theme park, there will be an off period more on weekends than on weekdays."

Gerdi Scheffler, of Salt Lake City-based Great Basin Travel, tells her clients to avoid visiting Disneyland in summer if at all possible. Holiday periods such as Christmas or any three-day weekend are particularly bad. She also recommended checking the Anaheim Orange County Visitors and Convention Bureau to see if any major conventions are in town that could draw large crowds to the park.

"The second half of September and the month of October except during the UEA (Utah Education Association) holiday is a great time to go," said Scheffler. "The weather is obviously nice. I would think the last part of April and first 10 days in May were times I would pick to go and there is also the end of January but the weather might be questionable. Spring break is horrendous."

The downside of visiting the park during a slow period is that hours are shorter and some major attractions are closed for renovation or in preparation for an upcoming holiday. For example, in September, the

Haunted House was dark as workers readied it for Halloween celebrations and Small World was closed for a major renovation.

Small World, which will open in a few weeks for a Christmas show, was closed for much of this year. It will be dark for most of January and then open with a revised and newly improved display.

Disneyland spokesman John McClintock said the busiest seasons at the park are between Christmas and New Years and when school is out in July and August. Weekdays after Thanksgiving and before Christmas are an ideal time to visit, especially since all the Christmas decorations and entertainment are up and running.

Also, in order to cut down on staffing, some major rides do not operate with all the trains or cars running when the park is not crowded.

McClintock said January and February are usually good months to visit, though the park does offer special discounts to southern

California residents that can bring some crowds.

Sehlinger said picking a day of the week to visit is tricky, largely because Disney offers early entry programs some days to those staying at its hotel properties. He said travelers with flexibility who aren't staying at a hotel with those privileges should avoid those "morning magic" days.

"People at Disney understand that when the park is crowded, it is not good for first time visitors," said Sehlinger. "So they lay out more live events like concerts and parades during the holiday period.

Because Disneyland is comparatively small compared to Disney World, you feel the impact of the crowds."

The bottom line is that to enjoy your happiest day at the place that bills itself as the happiest place on earth, do some research and avoid holidays and summer months if possible.