First thing I always suggest to do is look at the Googlemaps aerial views of the resorts, ZOOM in, and see how you feel
about the footprint and layout of each resort. (See links below.)
Next look at the resort photographs online (see links below). They virtually show everything you'll see and experience
while at each place.
You'll probably come away from that exercise with a pretty good assessment of a favorite.
Let the family members sit down together and share all the visuals, and comment and critique both resorts out loud.
Go with your collective gut feelings.
Pictures are worth a thousand words, and they will mostly influence the gut feeling. Everybody on TUG has different feelings
about these two resorts, and probably 50% leans one way, the other 50% leans the other way, so imho,
I'd do the homework myself and only allow certain words from others to contribute to YOUR family's decision.
If everybody has a hand in the decision, it'll be more enjoyable. (You COULD stay a week at each, right?)
Both are amazing resorts, neither is better than the other; they're just so different.
Grande Vista is a more active place, and it's huge and has a million activities.
photos:
https://www.marriott.com/hotels/hotel-photos/mcogv-marriotts-grande-vista/
aerial view:
https://goo.gl/maps/pxmaXfGsBgjBwf748
Lakeshore Reserve is more laid back, more "refined", and will be a bit more relaxing and imho, more upscale.
photos:
https://www.marriott.com/hotels/hotel-photos/mcolr-marriotts-lakeshore-reserve/
aerial view:
https://goo.gl/maps/VgHaHyfhiU8LYGLH6
Keep in mind, at LR, you have access to the adjacent JW Marriott Hotel and the Ritz Carlton Hotel, and both are awesome,
with gorgeous pool complexes and grounds.
aerial view of LR, JW Marriott, & Ritz:
https://goo.gl/maps/rKHBXHTYh7XcStXz6