If you can already swing the price of the extra night in the hotel and the extra night on the dining plan, these are what would considerably change the price of your vacation, not the tickets.
Go for 8 days and options for tickets:
1. Still only get a 7-day ticket with PH (you only have to get a 1-day for the MYW package and not the number of days of your trip - that's only for the dining plan) and plan a non-park day
2. Get an 8-day ticket with PH - the price doesn't change much
We like the PH option and always get it, but we are not traveling with any children in strollers (as it sounds like you are) so we are able to hop pretty easily. Also, as a previous poster stated, we like the ability to start our day in one park and end in another. But, we do not focus on getting all the rides in - we just stick to our favorites. We also like to make several ADRs during our trip and having a PH allows us to not worry which park we will be in when making our dining choices. We hop pretty much every day of our trip, so a PH is a must for our touring style.
Ultimately, it really depends on your touring style and expectations. If you are planning to try to experience all a park has to offer, hoppers are not necessary because you can easily spend a whole day at every park. Yes, even at HS where so many things have been closed!
To sum it up, my vote for you would be to do the extra day AND park hoppers, but if it's one or the other, go with the extra day.