You cannot add a Guaranteed Week to your existing contract. I own a Guaranteed Event Week contract, so I know a bit about them.
First, it's helpful to note there's a difference between a Guaranteed Week and a Guaranteed
Event Week. A Guaranteed Week works much like you would expect a typical timeshare. You buy an entire fixed Sunday through Sunday week corresponding to a certain number of points, and DVC will book that week for your before the 11 month window opens. You are guaranteed the accommodations you purchased every year without fail unless you opt to cancel the week (which you can do at any time). These were/are offered at PVB, GFV, AUL, CCV, and RIV.
An Event week is similar, except they correspond to the 4 runDisney weekends - Wine and Dine, Marathon, Princess, and Star Wars (or I guess, Springtime Surprise now). Event weeks are assigned a week just like a Guaranteed Week - for example, the Wine and Dine week is contracted at Week 44 - but they are fundamentally different in that they "float." Member Services will call you ahead of the booking and ask what days you want to book. You don't have to book Sunday-Sunday. You can book Tuesday-Tuesday, or even Thursday-Monday if you don't want an entire week. And your booking is guaranteed every year once MS sets that date. Also, the contract includes guaranteed early event registration, with a link sent to you by MS before general registration opens. Guaranteed Event Weeks were first offered at CCV and they were discontinued for RIV, so if you want one you have to buy CCV.
Thanks. Not sure why I never heard of this. I was intrigued that it says it secures race entries.
I don't have my contract handy so I'm going off memory, but as I recall you are allowed 5 race entries for your specific event for yourself or anyone else you choose to register. The entries can be used on the 10k, HM, marathon, or challenge - no 5k or kid's races. And note it's only for the event you purchased. If you buy a contract for Princess, you cannot use your race entries on any other weekend if you don't use all 5 for Princess.
My understanding is that once you purchase a gw, it's set - you can request to just get the points in lieu of the week, but the request has to be made every year.
This is correct, but you don't have to request it every year. For a regular GW, the booking is made automatically for you, and you can cancel it and use the points if you wish. For an event GW, MS will call you before they make the booking to get the dates you want.
Which is exactly why this doesn't sound like much of a deal. If the event itself is not guaranteed, what's the point of paying extra for a guaranteed event week?
If for some reason the event is cancelled, the week reverts to the underlying week stipulated in the contract. W&D is week 44, and the rest I don't know off the top of my head. Those weeks can still be cancelled and the points used however you'd like.
RunDisney events are usually during "slow" times anyway, so DVC reservations aren't hard to get for those events if owners take advantage of early booking windows. Personally, it's never been an issue for me getting a room for those events when booking in advance.
I don't know when or what you are booking, but this is
extremely not true. Studios book fast all race weekends and are very hard to get at certain resorts if you do not book 10-11 months in advance. If you're booking AKV, OKW, or SSR I can understand why you may think this is easy. For anyone who owns and wants a studio at GFV, CCV, RIV, BWV, BCV, and sometimes even PVB it is very hard to get a studio on a race weekend. CCV and BWV standard studios are gone pretty much as soon as the 11 month window opens. It's unfortunate that CCV is the only resort that has the guaranteed event week, but if you want to stay in a studio at CCV during runDisney events, you better be booking right at 8 am or you may be out of luck. That's the value of the contract.