Disclaimer: First post from a brand new timeshare owner!
I have a travel background that's similar to the OP in several regards, but different in other ways. I'm a very frugal traveler, and over the years I've used several methods for getting great prices:
1) I'm a huge fan of Priceline (and to a lesser extent, Hotwire), and have had my share of great deals through them. It's awesome to get a Marriott for less than a Motel 6 would cost. With the rooms only guaranteed to be able to sleep 2 people, this isn't a good option for families.
2) I own my own business, and charge a considerable amount of money to Hilton and SPG Amex cards, giving me tons of points that I can redeem for hotels when I can't get good rates in other ways. The Amex spending also earns me SPG Gold and Hilton Diamond status, which gives me some upgrades and other perks. I value my points based on the cash I would earn if I used a 1% cash back card instead, and only use them when I can get a good value (usually 2-3 times what I would have earned with 1% cash back) out of them.
3) In the current economy, in many places I can find good Hilton family hotels (Hampton Inn, Doubletree, etc.) in the $80/night range. Especially when there's a chance of an upgrade (with my status), that's pretty decent. Plus, I earn 39+ HH points back per dollar spent, which is essentially a 20% rebate (I value HH points at half a penny each).
Our family is a bit unique in that we have the means and availability to travel as much as we want. I can work from anywhere. My wife is a stay at home wife/mom (although she did start her own business last year). My kids are homeschooled. We traveled something like 100 days last year. One of our passions is Disney. This will be our fourth year in a row to go to WDW for 2 weeks. We got Season's Passes to DL last year and went three times. We went to DL Paris earlier this year.
We've been planning to take a 3-month Round The World trip seeing about 10-15 places in 2012. I have almost enough AA miles banked to buy the airline tickets (in Business Class!).
One challenge we're running into is that we just had a third kid in April, and many hotels don't allow more than 4 people in a room. In Europe (and some other parts of the world), many don't even allow 4. You can just ignore the fire code and sneak a fifth person in, but I'm not really comfortable doing that and the rooms get pretty cramped with a larger family.
We went to a timeshare presentation on Wednesday, and I realized several things (other than the fact that timeshare salesmen are liars). I realized that a timeshare would give us the ability to travel as a larger family. I realized that a timeshare and RCI membership would open up another option for discounted lodging (Last Call, Extra Vacations, etc.). I realized that we could be far more comfortable and could travel even more, especially with our flexibility.
And then I made a stupid mistake. I bought a timeshare. From the developer. (And I knew better!) I quickly came to my senses, though, and in less than 24 hours my notice of cancellation was sent out via certified mail with return receipt.
And then I made a good decision (I hope). Thursday, I bought a 3BR Lockout at Summer Bay Resorts in Orlando on eBay for $1. The maintenance fee is $860/year.
This does several things for us:
1) It gives us a really nice place to stay (compared to the types of places where we normally stay), just 6 miles from the WDW entrance. If we don't want to exchange it, it's something we wouldn't mind using every year. If we do want to exchange it, it seems like a 3BR in Orlando would have fairly good value (but I could be wrong on this). If we want to invite friends or family to come with us, we'll have plenty of room. (I don't even know if it's a Weeks or Points timeshare yet, but either way is fine for me at this point.)
2) It opens up RCI Last Call and Extra Vacations for us, which from what I understand would have some tremendous values (often $50/night and less). At the very least, it opens up another choice for us.
3) It makes our RTW trip much more feasible, in that we can find and book resorts that accommodate more than 4 people (and hopefully at good prices). Many would also have kitchens and laundry, which would also be extremely helpful.
So that's how I think this timeshare will save us money and give us considerably more flexibility and comfort. I realize that some of our circumstances are pretty unique, but parts of my thinking may help the OP or someone else.