I'm in the same boat as OP. 15 months old and I'm worn out from all the constant stimulation he requires. I am home with him 4 days of the week and his dad is with him 2 days, then we have two nannies that come during the week to give us a bit of a break. They can entertain him and have all the patience in the world for his constant curiosity and movement. That has been our sanity-saver.
For stimulation though, we kept locks off of most of our cabinets/drawers (unsafe stuff locked up in a couple off-limits places) and let him lead where he wants to explore. Often times, we head outside the home to keep things at home from getting completely mundane (we also rotate toys and what is in drawers/cabinets). The yard, parks, museums, aquariums, malls, playgrounds, farms, play places, ice cream shops, coffee houses, or anywhere that will give him some new experience.
During diner, I involve him as much as possible. He throws away all the stuff I need put in the garbage, he is my taste-tester, and stirrer, he hands me my oven mitts, and he gets his chair and dishes ready. If we are doing something, he has to be helping.
