I'm so glad to see what I did was normal...
My son was 3.5 yrs old when his twin sisters were born. It was a good age gap for me as he was at the stage where he wanted to help with everything and wasn't completely dependant on me for every single thing anymore. But keeping a balance between caring for not one, but two babies and still care and play with your older child is not easy. I too allowed way more tv than I'd like to admit when I ran out of ideas or hands or time or whatever.
What worked great for us though, even though he was a boy, was to give him a doll to copy what I was doing with the babies. When I sat down to breastfeed, he'd cuddle and nurse his doll. When I changed nappies, he changed his doll's nappy and so forth. It helped him to feel part of everything and we never had issues that he became jealous of his sisters. And it was only for a few weeks that he needed the doll before finding other ways to keep himself busy when I couldn't spend one on one time with him.
He loved puzzles and lego blocks and this could keep him happy for pretty long periods of time.
It's probably not the type of answer you were looking for, but I wish I had a better support system back then and knew that these things were normal to "life with twins". I cried the first 18 months away, I was so overwhelmed!! Only now that the twins turned 3 yrs old did I start to feel more human and able to cope with three kids better. When people tell me I'm "a supermom, how do I do it?" I reply that I cried the first year and half away and they have a total look of shock on their faces LOL!
It's not easy, but somehow you survive, manage and get through it.