Which is more economical - using out central heat that uses propane or using several electric portable heaters?

The home that my husband and I moved into two years ago that runs off of propane. Our propane tank is 250 gallons and it cost us $525 to have it filled up about a month ago. Having spent over $1600 on propane over the course of four months during our first winter here, we decided it would save us money to invest in electric, portable heaters. We have a larger home (2200 sq. foot), our living room is about 500 sq. feet with 18 ft. ceilings so it has been difficult finding anything portable that can efficiently heat that space but have been using a small, portable, electric fireplace, along with a radiator type heater in the master bathroom, which also is the heat source for the master bedroom, a larger, ceramic heater with a thermostat in the hallway where our children's rooms are located and one small, tabletop, ceramic heater in my oldest son's room. These heaters are only on when we're home and when we're awake. They are shut off at night and when we're not home. We purchased some electric blankets for our children's beds that have a 10 hr. auto shutoff feature but I'm overly paranoid about fires so I always shut them off before I go to bed. Anyway, long story short, latest propane bill was $525.00 to fill up the tank. It would probably last about two months if we used our central heat as our sole heat source. Our most recent electric bill was $250.00, which is the highest it has been since July. So obviously, either way we go, it's not going to be cheap. I'm just wondering if there's something out there that's great at heating larger areas, that's safe to have around children, low cost and efficient, that doesn't require renovating your home to install it. Any suggestions? At this point, I'd rather just strictly use the central heat. It might cost us $500+ every couple of months but at least we'd be warm and I'd have my piece of mind at night. My husband on the other hand prefers to leave the heat off altogether because he hates that propane bill.