I love the toddlers, but I've only played more than one a few times. (It's very cute to see them interacting with each other - that's just one of the things they improved over previous Sims.) But, generally, I don't like to have more than two Sims in the household, no matter what their ages.
I like the 'clingy' trait, and the 'independent' trait can be useful. 'Inquisitive' doesn't seem to do much. 'Wild', I tried once and never again.
As others advise, chuck the high chair. Most of the toddler foods overfeed the kid (if she doesn't throw the food on the floor - grrrr). I feed mine a plate of superfood salad in the morning and just before bed, and it's just the right amount. (I also keep some fruit in their inventory in case they need a boost late in the day.)