It is so nice to have the ease and convience of being onsite. Plus if you need a mid afternoon break from the parks you will be a short bus or boat ride from your room.
You have the *chance* of getting a *short* ride back.
You also have the chance of it taking 2 hours to get from DHS to OKW, like my husband and aunt experienced in December 2010. (they still don't trust Disney transportation after that)
What are the benefits of being onsite to you? In two *long* trips I think we've hit EMH exactly once, and honestly it didn't feel that fun to me. (on the other hand, at
disneyland we attend Magic Mornings whenever possible, because MM is absolutely positively a benefit, without the controversy/other opinions that swirl around EMH) We have rented a car each time, and while we have never had a problem or delay with driving to and from the parks, our Disney transportation experiences have been less than fabulous. We have *never* used their package delivery service. etc. For *us*, onsite vs offsite isn't really a huge deal (though we bought DVC without even going to WDW because we knew we would want to go again and again AND we thought being onsite would be more beneficial than it has been).
What does it mean to YOU, though? If you have parking budgeted, or someone will have an AP that gives you parking, then that's not a problem. If you know the area and won't get too turned around in driving to and from, then that's not a problem. If you like to carry packages around with you (or, I think WDW does the "deliver to the front of the park" thing that DLR does, you can use that) then you don't need the delivery to your resort benefit. And if you can just avoid the parks with morning EMH, then that's not a benefit you need, or that will mess you up, either!