I agree with a few of the posts above. While it appears that you've thought it out, deciding to buy into Chairman's level right away is akin to diving in head first. Perhaps buying into Executive level with a hybrid package would be like dipping your toes into the pool. It'd give you a chance to fully experience the program, while having the ability to rent points from others to take full advantage of a larger points package without the upfront or annual MF commitment.
Let me preface it by saying we're very happy legacy week owners, and we love going to Aruba. Generally we go twice a year, and will lock-off when the studio isn't needed giving us a trade elsewhere. Using that we've also gone to a variety of other places, although not nearly as many as others on this board. Whether or not we have the kids/grandkids with us we prefer the timeshare lifestyle, but not everyone does. I prefer to be able to have breakfast in my villa rather than going out most days, and like to bring down a cooler and graze at the beach. Most nights we go out to dinner but really like breaking it up and grilling maybe 2 nights during the week. And I'm fine planning a year in advance, reserving the week I want at the earliest possible date to reserve (and, yes, on occasion I've changed it due to a conflict). I don't need fresh linens every day and don't mind straightening my bed, and enjoy the convenience of a kitchen and added space. That said, there are many people who prefer daily housekeeping (although available at an added cost), hate advance planning, miss room service and the larger restaurant selection found at many resort hotels, and prefer more luxurious hotel amenities.
Like others have said, timesharing isn't for everybody. It's a more economical way to visit really nice resorts in great locations with spacious accommodations and with nice but not high end amenities. If you require secluded beaches and private dinners, someone bringing towels and cold water to your lounges, etc., then staying at a Ritz or St. Regis or the like will be more to your liking. On the other hand if you're looking for a more economical, spacious but still really nice travel option, then you'll likely be very happy. But you need to experience it for yourself to know if it's right for you.
It's much easier to buy than to sell, so I wouldn't rec. starting out with a 100K investment and high annual MF commitment. You mentioned Aruba in your original post. Did you enjoy your visit there? If you could envision wanting to return for your annual June trip every other year or so, a nice option might be to buy a resale 3BR Gold season week there. The units are huge, and would comfortably accommodate your group. The second bedroom has 2 Queen beds, good for your daughters and friends, and the lock-off is huge, a bit down the hall and has it's own entrance, so ideal for non-family guests. It trades well so would give you other options. If you buy one on the resale market you won't be able to enroll in the points system, but it's a great way to dip your toes in the water, so to speak. You also mention Orlando as being a frequent past destination. If you foresee that for the future, then a 3BR Grande Vista week might be something of interest. Just mentioning these as options, since in today's market the 3BR Gold Aruba week would prob. run ~12-13K and the MGV less than half of that. The annual MF's for the Aruba week is ~2500 and the Orlando week I'm guessing closer to 2K, so you could see if this is right for you with far less financial commitment. IF you really want to enroll in the points program IF Marriott has any direct resale 3BR weeks in Aruba those are eligible to be enrolled, but you'll prob. pay triple the cost up front.
Anyway, just some food for thought. Good luck, and welcome to TUG