If you don't want to subscibe to the website, you can purchase (or check out from your local library) the book "The Unoffical Guide to Walt Disney World" and they have several touring plans in the back of the book, plus the book has great tips and info in and of itself. Get the new 2006 version if you can. These touring plans are designed to give you the shortest wait, which means that you may have to walk past rides you plan on riding, and double back later. It means more walking, but overall less waiting.
If you'd rather not purchase the book, you can follow some simple rules to help minimize your wait.
1) Get to the park before opening.
2) Get to the park before opening.
3) Get to the park before opening.
By before opening, I mean actually be in the park before it opens and be present for the "rope drop". Disney 9 times out of 10 actually lets people thru the turnstiles before the opening time, and holds them just in side the entrance until they "drop the rope" they use to hold back the crowds. If the park opens at 9 AM, you need to be getting to the park at about 8:30, and don't forget to allow time to get to the park by bus/boat/monorail. Yes, they all run early.
4) After the rope drop, head to the most popular ride that you plan on riding. In MK, this could be a tough choice, as younger kids want to go to Fantasyland, and adults/older kids will want to ride one of the "Mountains" (ie Space, Splash, or Thunder). If you are not using the Unofficial touring plans, I'd either split up and have the older kids go with one parent to the big rides while the other parent takes the little ones to Fantasyland. If you cannot or do not want to split up, then go to Fantasyland first, as lines there are worse, IMO, than the big rides. Then hit the bigger rides, using Fast Pass as needed. For the other 3 parks, just hit the big ones first, and do the smaller/less crowded rides and shows later.
5) Be where the crowds aren't. Unless you've got a kid that HAS to watch the parade, try to ride rides during the afternoon parade, lines can be a bit shorter then. Also, try to eat at off times, lines at counter service can be insane if you go during the normal meal time. There are excepetions to the "ride when there's a parade/show" rule when the parade/show is so specacular, you don't WANT to miss it. IMO these would be Wishes (fireworks) and Spectro (nightime parade) at MK, Fantasmic at MGM and Illuminations at Epcot. Unless you've seen them a ton of times OR have plans to see them some other time on your trip, don't skip them to ride rides, you really want to see these.
6) Tour the parks in the rain. With so many of the rides being indoors, 90% will still be open while it's raining, but the hoards will mostly pack up and leave. But if there is lighting, stay inside until the lightning stops!
7) Tour the parks late. Especially if you don't have "little ones", stay in the parks until close, most families leave (relatively) early when the kids start to poop out. This is especially true when the MK is open past 9 or 10 PM. You can go to the park for opening, leave after lunch to rest and relax at the hotel pool, then head back to the parks after dinner and stay until close.