Well, I'll try to explain...
If you only plan to visit one park each day then, you do not need "park Hopper" tickets. Those are only for when you plan to visit multiple parks in one day. So, you would need to purchase 2 day base tickets for each person. It will cost a lot more if you buy 1 day tickets for each day that you plan to go. Now, keep in mind that some people do not consider MGM to be a full day park (my self included!). It would be sad if you finished everything there in half a day and then coudl not go to another park that same day. So, given that, you may want to consider paying the extra amount for the park hopping. Another thing to consider (and please ask to make sure before doing this) is that you could buy the base tickets and then if you decide that you would like to park hop after you get there, go to guest services and upgrade your tickets to park hopper tickets. You will have to pay the difference on both days tickets and I believe that you can only do this in certain locations. I'm sure that someone on here can shed some more light on that subject.
Another option would be to purchase tickets that are good for more days and add the no expiration option. It may seem a little crazy to purchase tickets for days that you won't be there but, you will probably go back sometime in your life and the
ticket prices will only go up! Once you buy non-expiring tickets, they are good forever so, you can look at it as an investment in a future trip. Plus the more days that you add to your tickets, the less you pay per day! 1 and 2 day tickets are very expensive, for example from the prices on Disney's website before taxes:
1 Day Base Ticket: $63
2 Day Base Ticket: $125
2 Day Park Hopper: $165
7 Day Park Hopper Non-expiring: $301
10 Day Park Hopper Non-expiring: $377
Sounds Crazy up front, but with the 10 day ticket you would be paying $37.70 each day! That's like getting almost half off the 1 and 2 day rates, not to mention that you would be adding park hopping and non-expiration!
I hope this helps and doesn't cause more confusion!
Have fun on your trip!