OP: You've already booked your park reservations, right? Just checking, since purchasing G+ or ILL$ doesn't give you an automatic park reservation.
So, assuming you already have park reservations . . . do you need G+ at DHS? It all depends on how many rides you want to do there, how long you plan on staying in the park that day, and how much standing in line you can put up with in the heat.
Early Theme Park Entry at DHS will get you multiple rides only if those rides don't include RotR, SDD, or MMRR. If you get in early and get in line for one of these rides, that is the end of your ETPE advantage. By the time you get off, the park will have opened for everyone and there will be lines for nearly everything.
But if you're going to ride TT and RnR, you can do both--assuming everything's working--at ETPE and then get in in line for whatever you'd want to do next. TSM would probably still not have a long line at that point, but the big 3 rides listed above will.
The lines for SDD and MMRR have major portions outdoors with little to no shade. That's something else to take into consideration.
We always get both G+ and ILL$ (for RotR) for DHS, but there are only 2 of us. There are 6 of you, so it's an extra $95.88 (I've included the tax here), which is significant.
If you use ETPE, get a certain number of things done, then take a midday break--it's July and you'll need it--and come back in the evening, you'd probably be able to get a decent amount done. As it gets closer to park closing time, ride wait times are usually inflated and it can be a good time to catch the attractions you weren't able to do earlier.
If you don't mind buying G+ and you want to have a relatively relaxing day, you could just skip ETPE completely, start booking your G+ attractions at 7 a.m., and stack your rides for the late afternoon and evening. It'll take some "work" on your part, since you'l have to monitor what times are available when and you'll have to be on your phone's app every 2 hours to do the stacking, but that can work really well.
Even if you use ETPE you can still make a stack for the late afternoon/early evening and use that stack when you come back from your midday break.
But . . . money. I get it. Only you can know if this is worth it for you and your family.