I've wondered the same thing as you. Will my kids be so spoiled that they don't even realize the "magic" and good fortune that they have? We have brought them to WDW nearly every year since they were 2. And twice in the past 12 months (yes, they really are SPOILED)

. After this we have a trip planned to DL and southern California for the fall. Sooooo...my DH and I decided we will probably take a year off of "disney" after our DL trip. Instead we may choose to visit Disney's Hilton Head Island in the fall of 2006, and include visits to Savannah, Charleston and Washington DC.
There are SOOO many places we want to see....and so little vacation time! We want to see Alaska, the southwest US, northern California, Europe!!! We tend to just say "let's do Disney" because of course it's wonderful fun and second nature for us. But we are really going to try to expand our horizons a bit more as the kids get older and can appreciate other places. But IMHO, there is no better, more kid friendly place than WDW. So it's just such an easy choice for those of us with young kids. And darn if it on EVERY trip something really special, really magical happens that makes us look at each other and say "can we really stay away from Disney?".
As for other options for travelling with young children, my recommendations are:
Cruises!!! They are wonderful...and a great way to see multiple destinations in one trip. However I do recommend them for children over the age of 3 because of age limits on the activities.
Skiing/Snowboarding. My kids have a blast when we do our mini ski trips to Vermont. They get so much fresh air...and it's great quality time. Of course...if you're not into the winter sports this is not an option LOL!
Laid back beach trips....we really enjoy our quiet beach vacations. We aren't running ourselves ragged...it's just lots of fresh air and lots of family time. With toddlers it does require more "work", as you need to watch them like a hawk. But we really love the beach and find it to be one of the best ways to spend family time. Renting a cottage, house or condo makes it very easy as you can cook your own meals and really relax!
Hershey Park!!! We love Hershey. Next to Disney it's our favorite park. Lots and lots of kiddie rides, tons of decent hotels and you can even extend your mini vacation to include a trip through Amish country.