Welcome back to the Disney Parks Moms Panel, Travis!
I completely understand your concern. A few years ago I brought two of my children to Walt Disney World Resort. They were 8 and 11 at the time. As it turned out, there were quite a few attractions where the three of us could sit next to each other. Many rides have rows of bench-type seats that will easily accommodate parties of three. On others, even if you won't all fit in the same row you would be in the same ride vehicle. Most of the coaster-style attractions only seat two Guests per row, but as a party of three you will be assigned consecutive rows so you will be able to sit in the row behind your sons. I'll highlight a few attractions where you may not be able to all sit together.
At
Disney's Hollywood Studios, each Guest will want to have their own shooter to play the carnival games at
Toy Story Mania! Each vehicle seats 4 Guests, 2 per side. Here you are seated back to back, so you won't be able to see the other Guests in the vehicle with you. Over at
Alien Swirling Saucers, I think it would be tight with 3 in one rocket. You would be assigned nearby rockets during the same ride cycle.
At
Magic Kingdom Park, there are several attractions that could be a bit tight for 3, but doable, including
Haunted Mansion,
Peter Pan's Flight, and
Under the Sea ~ Journey of The Little Mermaid. Rides where you will need to split up include
Tomorrowland Speedway,
Astro Orbiter, and
Buzz Lightyear's Space Ranger Spin.
All in all, there are many more rides where you will all be able to sit next to one another than those where you might need to split up. Even in those cases, you would still be able to be near each other.
I hope that helps! Please stop by the Moms Panel again with any additional questions you might have. Have a wonderful trip, and have fun making all those magical memories with your sons!
Anne Marie