Well, first let me say that it's NOT weird to be a single rider. I was a single rider every afternoon of our trip as DH stayed at the hotel with our girls when they napped last year.
It might be easier to list the rides that DON'T limit to 2 seats. It seems like most are built for 2. Almost all the dark rides are 2 seats (e.g., Snow White, Alice, Toad, Peter Pan, Haunted Mansion, Little Mermaid, Buzz).
So, off the top of my head, rides that ARE NOT limited to 2 seats:
- Some of the open-air ones like Mad Hatter Tea Cups, the DLR Railroad (it's a ride in my book!), Grizzly River Run, and Storybook Train can accommodate more than 2 (the train has some 2 person only seats but also has the "cages" that can fit more people).
- It's a Small World (IASW) and Pirates
- Indy
- Matterhorn, Goofy's Sky School, Big Thunder Mountain RR, Space Mountain and Splash have 4 person sleds/cars/logs so at least you're not entirely alone if your 2 teens are in the other section of the same sled/log.
- Many of the Paradise Pier rides aren't limited to 2 (e.g., Mickey's Fun Wheel, Golden Zephyr, Jumpin Jellyfish)