These comments are just from our own experiences, we've been to the World over 38 times, is we always book room only. I've looked into the packages and knowing what we like to do and see, take the package listings and do the math. We could hardly do everything in most packages, being we would have full park tickets for the duration anf feel we would not get our fare money deal. We like to relax some at the resort pool, feel its good enough instead of heading over to a water park which we could do and just pay for out of pocket. As for the other offerings, like PI and DQ we're not interested in having done those on other trips and really didn't care to retry them.
That all being said, we just like paying for what we like and can do without racing around trying to get it all done. Time of the year means alot if looking into packages, to us not worth it if its the cooler months in Disney nor really good during the hot summer months with huge crowds. TL and BB can be real crowded and not alot of fun and if its cool out that wouldn't be great either, then that part of the package is lost. I guess it boils down to what spare time you have in your itinerery, time of year, season and length of stay.