I second the idea for wall tapestries, that was the solution in the middle ages for keeping large areas warmer =)
How about this … a mock tent, I saw on a decorating show a bedroom made into a faux hindi indian space by making a faux tent out of the bedroom. Make a faux tented area like a diwan space as a conversation pit, so the heat from a space heater and bodies are retained.http://c.photoshelter.com/img-get/I0000jt5sHLJAbYM/s
What kind of flooring do you have? If it’s not carpet, area rugs will help: you can roll them up and take them off in the warm months. Have them under the table where you normally eat, your computer desk, a small one to the side of the bed… and something as simple as moving them around counts as redecoration (which is a bonus for those of us who get redecoration bugs every half year).
I’m not familiar with those plastic sheets being described, what we use in Spain is foam tape (“burlete”) that goes all around the window/door (if it’s rotating, if you have a guillotine window the tape should be on the bottom only), stuck to the frame in between the frame and the moving parts, so it all closes very tightly. If putting your hand close to the window’s edges without touching it finds a cold area, see if you can find those. I know 3M makes it, but not whether they sell it in the US.
“Loft” implies a higher floor, like 3rd story or higher. Is a waterbed an option? They suck for higher floors, but can really heat up the kind of space you describe.
Wow, thanks for all the suggestions! I definitely have a few things I’m going to look into now… We rent our apt, so we really wouldn’t be able to install a better heating system or add ceiling fans or build anything. The one ceiling fan we have is all the way on one side of the apartment near the windows and it doesn’t have a reverse setting, so it actually feels like it is making the place colder. I think I’m going to try what a few people mentioned here and use some regular fans to move the air around…
The building we live in isn’t a traditional apartment building, we live above a restaurant and below 2 other loft-style apartments similar to ours (however I’ve been told they’re smaller and I know they have much smaller windows)… I don’t see my neighbors very often but next time I do I’m going to ask what they do…
We have hardwood floors and we did put an area rug underneath the bed, maybe we can get a few more… I’m thinking that it would be difficult to section off different areas of the apartment. The kitchen is on one side and the bed\PC area is on the other with the couch and TV in the middle. We use the entire space all the time, we’re not ever in one section for very long (except when we’re sleeping)…
The 10x10 windows are single pane and seem to be allowing a lot of cold in. I’m definitely going to try the plastic sheeting, I think I’m going to attach it to the frames with a staple gun. The curtains seem to help as the area between the curtains and the windows are like 20 degrees cooler than the rest of the apartment. I like the Velcro idea to attach them to each other, they overlap but I’m sure air is still making its way between them… The “tent” idea is also very interesting, I’m going to look into it…
Other than that I think I’ll get some more space heaters… I’ve seen a few comments that indicate Canadian units are better\hotter than US ones… Is this true? Is it due to government regulations or something? Would it be illegal for me to purchase a Canadian model and use it in NJ?
Thanks again for all the suggestions…
No no no no no. Do not do this! All you end up with is plastic sheets stuck to a window frame with staples (and lots of holes in your wall!), but it isn’t sealed or insulating at all!
What you need to do is buy something like this kit which comes with more than enough two-sided tape and the large sheet of plastic which you can cut to fit whatever windows you have. Look in your hardware stores. The tape goes along the outside of your window frames, then you place the plastic about as tight as you can across it, making sure the whole thing has no air gaps around the edges, and then you shrink/tighten it up with a standard blow dryer set to Hot. If you do it well, you can barely see the plastic over the windows. The tape comes off really easily in the spring, but I don’t recommend leaving it year-round as the previous tenants did here, because then it just gets dry and yellow and it’s a pain to remove.
My husband would have to dig out our records for the past four years, but we didn’t put the sheeting up our first year here and he says there was a significant reduction in our heating bill in the subsequent winters, because this stuff really does insulate very well.
Double sided tape is going to do a better job than a staple gun. You are looking to trap air in between the window and the plastic. Tape will give you a much better seal.
Another thought. Do you have a humidifier? I live in a cold climate, and the air in our house gets very dry. We run a humidifier and humid air at the same temperature feels much warmer than dry air does.
You mention that there is another floor above yours. By any chance is there an open stairwell between the floors, and do you have gaps around your door(s) into the stairwell? At one time, I lived on the top floor of a building like that, and we didn’t have to heat much at all. You could feel the warm air drafts coming in under the doors.
And three dogs each…
Seriously, try more fans - I have a cathedral ceiling and keeping fans on low (blowing up) almost evens out the up and downstairs rooms - which are 5 F apart with no fan.
Sealing the windows also good but even sheer curtains will trap a layer of dead, insulating air around the windows.
I can’t imagine that Canadian space heaters are going to to be somehow better than American ones, unless they’re simply higher wattage. But even there, you’re limited by the circuit.
If this were a place you owned, I’d suggest installing some sort of radiant floor heating. Since it’s not, perhaps you can get an electric heating pad that could be installed under the carpeting.
I don’t see a problem with using Canadian-bought heaters in NJ; you’d want one that has a CSA International-approved symbol on them which is a standard for both Canada and the US. Get a good one or two, not a cheap one - space heaters is a case of you get what you pay for. I could be talking out of my ass here, though - I’m not an electrician. Just a space heater consumer. 
You could also get a heated mattress pad for your bed which is, I hear, one of the most amazing products available for sleeping toasty.