Cooling sytem problem

Ahhhhhhhh.... ^yeah I think it's definitely my radiator. Here's what I ended up doing today after a painstaking 9 hours of work:
Tried bleeding again, didn't work.
Saw a good old friend under the car.. LEAKING COOLANT!! From guess where? Another damn freeze plug!! I just replaced my passenger plug a week or so ago, today it was the driver's side plug that was leaking. After hours of pounding in a small tight place under the car, killing my back, I replaced it.
Bled again, still overheats!!! WTF! And my thermo still feels like it's not opening(cold lower hose, hot upper hose)!!
So then I said screw it, took out the new thermo(which still works after testing it in some boiling water) and replaced the water pump, which was real corroded and rusty, which also tells me the cooling system was mistreated by the previous owner.
Bled it again, and now it runs okay, but still gets a little hot when I idle too long.
Under freeway driving with a/c on it rides at a little above halfway 1/2 hash or so(which i'm sure is not normal)
Under street driving, it gets up to 1- 1 1/2 hashes above normal...
Oh, and now my heater does blow hot air, so the coolant is flowing, and the heater core isn't plugged.
Now knowing that my pump is new, my lower and upper hoses are new, the car doesn't leak coolant from freeze plugs, and my thermo is not installed, i'm left to believe the radiator is inefficient and not cooling the system enough.
Hopefully it will hold up for a few days until I can get a new radiator (any suggestions anyone?) and put my thermostat back in.
Thanks again for all the help everyone, and i'll keep you posted on the new radiator install!

Yup, i've tried several different ways to bleed the car, the main constant being the car is always on the ramps and I try to keep system topped off:
1. Take cap and bleeder screw off, fill with fluid til it comes out of bleeder screw, leave screw off, rad cap goes back on. Start car put heater on full blast, and squeeze both hoses til no bubbles, then tightened bleeder bolt.
2. Leave cap and screw off, fill with fluid, leave cap off AND bleed screw off. Start car, heater on full blast, squeeze hoses til no bubbles, tighten bleed screw and put cap back on.
--these methods i tried when I was doing various things like replacing thermo, water pump and hoses. I believe I let the car idle for about 15 mins each time.
3. Leave rad cap and bleed screw off, fill til fluid comes out bleed screw, then close screw, but leave cap off. Start engine, turn heater on to full blast run til it warms and continue to squeeze upper and lower hose. Put cap back on when I feel it's bled and absolutely no bubbles come out when squeezing hoses --this time I let the car idle for about 20 mins to make sure the thermo opened(which I noted by the lower hose heating up). This method seemed more successful as it didn't heat up so rapidly after I started to drive with the A/C on, and it even cooled down after I stopped at the gas station for some cigs lol. However, after about 10 more minutes of driving the temperature started to climbed, and reached second to last hash(when I started to drive on the freeway), when I turned the A/C off and heater on, the temperature started to go down. After turning the heater off and continued to drive on surface streets, the temp stayed at slightly above half.

So could it be that my A/C fan is just shot?? I do see it turning on when I turn the A/C on but maybe it's just not turning fast enough to cool the engine with the A/C on.

Updates!!

Instead of starting a whole new thread I thought I'd just update this one.
Once again, summer is here and my car is running hot to the point of nearly overheating. Though I can't say I've actually overheated because I've never let it get that hot, and the coolant is not boiling in the overflow tank when car is running hot (nearly outside the "normal operating range" on the factory gauge)

To recap what I've replaced and installed over the last year:
Water pump
Radiator
Nissan OEM thermostat
Upper and lower hoses
Found a bad clamp and replaced several clamps
Leaky freeze plugs(put in rubber ones to hold until I get my SR, and yes they are holding)
Cardboard upper cooling panel lol
Altima dual fans and DFI controller, no more clutch fan

Now the symptoms:
I've pressure tested the system, and it will hold 21.5 psi for 30 mins, but at 23psi(testing pressure) it will slowly leak down to 21.5 and hold.
Car doesn't visibly leak coolant, although it does leak oil from somewhere, and now seems to heat up somewhat slower than last summer. I can drive around for about 20 mins before the factory temperature gauge starts to rise above the halfway mark, and it will get up to the top of the "normal operating range" of the gauge if I drive for extended periods. Of course, the entire time I'm using A/C except when I think the engine will overheat. As a side note, ambient temperatures here in Vegas are around 100*-110*F.
Fans are coming on and even go into "cooldown" mode when running hot.
I also installed an electric Sunpro water temperature gauge and upper radiator hose adaptor to monitor water temps coming out of the engine. I don't know if this is good but as I was driving around tonight the Sunpro gauge was reading 190-200*F and the factory gauge was sitting just under the halfway point, ambient temperature was ~95*F, and I wasn't using A/C, that seems high or an incorrect temperature reading.
Sorry to make that a long read but again wanted to bring everyone up to speed with what I've done to remedy this problem, so to ask my 2 questions now:

1. 190-200*F seems to be a high operating temperature, especially since I wasn't using A/C. Is the Sunpro gauge off, or possibly my grounds are bad? I grounded the gauge inside the car and even grounded the hose adaptor. On both grounds, I sanded down to bare metal to ensure good connection. The gauge has a mechanical face and the sender is electric, if that helps.

2. Why is my car still running hot? Again, I never let the car actually overheat, and if I turn the A/C off the engine temperature actually does start to go down. Yes the factory gauge has been acting funny(as I've read these gauges do), hence why I got the Sunpro, but It does seem correct as it's not completely erratic, just somewhat bouncy when hard braking or cornering.
I've bled the car many times, taking about 15mins each time to "ensure" a proper bleed, yet the car still runs hot.

I'm going to monitor the temps on my Sunpro gauge and compare to the factory gauge over the next day or two and update what temps the Sunpro gauge is reading, though again, the Sunpro gauge seems to be reading a bit high at 190*F running temperature...

Any help with these questions would be great and hopefully will buy me some time until I can get my SR Thanks again folks! You are always helpful.

These are temp sending units