It depends on how many people as well.
We always travel with a 3oz travel sized bottle that we fill up with the sunscreen from a larger bottle that is left at home.
Personally we use Equate SPF 50 Sport, readily accessible at least during your park portion of your trip if you had to go to
Walmart to get more if you suddenly felt like you didn't have enough.
For my husband and I we would likely only need one 8oz bottle plus the 3 oz travel sized bottle. I brought two 8oz bottles and the one 3 oz travel sized to Cancun for an 8 or 9 day trip and didn't need the second full sized bottle. That 3 oz travel sized bottle makes a difference.
Knowing where you burn would also make a difference. My nose in particular and my top of my chest/neck as well as backs of my arms and shoulders are where the burns occur. I tend to put a lot on my face and reapply most there. My legs on the other hand don't burn much at all. It doesn't mean I don't apply or reapply sunscreen but that I know I don't have to concentrate as heavily as often on them and that takes out a larger surface area. My husband on the other hand can burn on his legs easier and his arms for sure, more his cheeks on his face but with what he's wearing not as much on his chest. Obviously for swimming we lather up everything and reapply everything once out but on a park day that is different (like we're not applying sunscreen on our backs for example).
But I also agree with bringing more than you need and if you're going to do checked luggage why not bring 2 8oz bottles? Bring a marker or pen or something to mark when you opened which bottle (or just to denote you opened a specific bottle) so you don't have two open ones at once. I would regardless recommend bringing a travel sized one. We just use one of the empty travel bottles you can grab just about anywhere and fill it up with the sunscreen (meaning you don't
have to buy a travel sized already filled sunscreen). If you're two adults it's probably pretty easy to bring two travel sized bottles with you. I do agree about aloe, in beach trips I've specifically brought that as well knowing that I have a higher chance of burning.