What other options should I be considering?

Tl;Dr I want to insulate or heat my living floor/downstairs ceiling.

So my house is weird. It's 2 stories, about 1800 square feet, but it's been puzzled together through the years. Aside from my bathroom and the freezers, we live exclusively upstairs for reasons I'll get to. 

Home construction is block, air gap, paneling in the downstairs living room, which is below the area I'm concerned with. It has a drop ceiling. Above the drop ceiling are the floor joists for the upstairs, they run front to back. Above that is old school 5/4 oak flooring, then if the bathroom is any indication, about 3 inches of plywood, before the carpeting in the dining room, lvp in the kitchen, and hardwood in my kids room. 

The child coming through the floor just sucks the heat out of the slightly under sized pellet stove on the far side of the upstairs. I want to do *something*to make this floor less cold.

I have already eliminated electrical heated flooring, the 200 square feet I'm looking to protect would run me almost $150/month in electricity, hell no. 

I'm considering water based, as I have clear access to all the flooring, but there are a lot of layers for it to penetrate, and I don't know if it would be any cheaper in the long run than electrical. Especially with getting another electric water heater and associated pumps for a closed loop system. 

Insulation batts will suck to get through the drop ceiling framework, but are another option I'm considering. Same with just cutting rigid foam board to fit the joists and nailing it up. 

I feel like I'm missing options but I don't know what they are. 

The rest of the upstairs is over precast concrete slabs, with some sort of a wooden sub floor assembly I haven't explored yet, so not part of this conversation at all. 

The downstairs was previously heated by the oil burner we rarely used, but being basically paneling over block, it really didn't heat up at all. I don't really want to turn on big electric heaters, but seeing as heat rises it could maybe make a difference, but again electricity costs. 

On my last place, the big living/dining/kitchen "great room" was above my garage. We found that heating the garage made a big difference to comfort of the great room. There was no insulation between them, just 3/4" oak, subfloor, etc. The garage was more or less underground so it would maintain heat well enough once you got it warm.

In reply to RevRico :

Insulation would help somewhat but occupied space over an unheated space is always tricky.   I get not wanting to run an oil burner any more than you need to, is there any chance of installing another pellet stove safely on the lower level?  Is it possible to tighten up the envelope on the lower level? Sealing up big air leaks will help a lot to warm the basement by itself.  

Edited to add:  In floor radiant is amazing comfort wise but you’d still need insulation below where the radiant would be installed.  It wouldn’t be cheap to install or easy based on your description.  

In reply to 11GTCS :

Down the road a ways, meaning after the upstairs gets rewired and insulated, we're looking to replace our current pellet stove with an insert style, and I'd been considering moving the current one to that room downstairs. 

I've already replaced the sliding glass door and covered the glass block windows with insulated blackout curtains. Draft blockers on the man door as well. I still need to replace the slat door going to the garage with something solid or at least not full of air gaps. 

Remodeling the basement living area to a space we'd actually want to hang out in was going to be our first priority, but I've got tile falling off the walls in the upstairs bathroom so it got dropped a bit on the priority list. 

What Tanner said.  Even a little constant heat downstairs will make that upstairs room much more comfortable.  heat rises.    You also noted the stove upstairs is undersized...

What area of the world are you?

Rugs/carpeting makes the floor seem "less cold" also.

YMMV

If your floors are really that thick, radiant won't work. And it doesn't matter if it's radiant electric, or water based. 
 

You've got a lot of thermal mass there. Thick floors, block walls. Draft seal the lower space and then add some heat to the lower level. It shouldn't be hard to maintain with all that thermal mass. 
 

Insulation is probably a waste of time, unless you use spray foam. 

How about purchasing another pellet stove for where the oil burner is downstairs? I agree that heating the downstairs a bit would help alot . After all cold air falls warm air rises. 

Anything other than properly insulating the lower level is patchwork, at best.  You have to balance the one time cost of strapping and insulating against the cost of the heat you are wasting through the walls. I grew up in a bedroom over a uninsulated crawl space with a leaky 4 over 4 window above my bed.   

I've spent a lot of money to make my 1962 house as warm and sealed as a modern house.

Streetwiseguy said:

Anything other than properly insulating the lower level is patchwork, at best.  You have to balance the one time cost of strapping and insulating against the cost of the heat you are wasting through the walls.

This is where I fall too. Rigid foam panels on the walls of the lower level would air seal and insulate at the same time. That might be enough to solve the current issue, and it would future proof the space to be heated in the future.