I've always liked Rio Verde. once you move the lot forward one or two rows forward, then remove the trees and shrubbery in the back and build a nice garden and have it walled off, it is actually a nice place for a multi-generational lot. with a few changes inside to allow for an underground floor, there is the capacity for additional stuff like a gym, a childrens play area, music room and so forth to really bring it out as an outstanding lot.
Oakenstead is another good lot to play on a multi-generational theme, with ladders being an option now, an attic is very possible now, that gives room to do other things up there. you also have room without adjusting the lot to create an underground floor as well. Once you get rid a few of the trees or move them around, you can expand the walls and put a pool down as well. So it too is a good place with an amazing amount of range.
Von-Widenburg Estate is also another good lot for expansion opportunity, however it does require a bit of adjustment though because it is a small house that covers about a quarter of the 64x64 lot. Once you remove the pool and other bits in the area and expand out that way a bit, it starts to look like a real gem with even more opportunity than Rio Verde or Oakenstead can provide. As it is, it's trying to be a 4 bedroom house, but it fails to make the cut and with some proper work to it, it can easily support 8 bedrooms, multiple bathrooms and so on.
Lastly on my list is Chateau Peak. The lot has one of the most amazing amount of range you can hope for, but it does require quite a bit of work to put it right. again only a quarter of the 64x64 lot is used by the house and the interior of the house will need a going over for sure as it fails to make the cut as a two bedroom house. once you have the money you can change it around a bit by expanding out a bit and get the most out of it.