At what age should a toddler make decisions?

Changing the diaper is not optional.  It's just, "Let's change the dipaer".  Don't let them decide about going to the store or you may be in for years of wrangling and negotiating.  Too many choices are overwhelming to toddlers but certainly it's nice to be able to lay out two choices (for outfits or lunch) and let the toddler have big girl/big boy choices.  Praise the choice when made.    As far as the TV shows, even those that are supposedly for kids can be inappropriate.  If you are familiar with the content of the shows and watch with your child then a choice of one or two is great.  It's really wonderful that you want to let them start making choices and move towards a little independence. A choice of two is wonderful and gives your little one a sense of independence and control.  A choice from too many choices can just be overwhelming.

Choices are very important for a toddler. They are figuring out the world around them and striving for independence. However, of course, they are still children and don't understand all the consequenses of some actions. We as adults do (or should) and that's why we set boundaries. Children as young as probably 18 mo can understand simple choices - "which of these two books do you want?" As they get older, give them controlled options, such as suggested above. Some things are nonegotiable, although, so do not give them the chance to become master negotiators - eg. bedtimes, running errands (your schedule), etc. I have seen 4 year olds bargain for every little thing, because they know that if they provide an option, their parent will give in.

So, I'll second the "everything in moderation" here. Give them the power of choice, in a controlled manner.