I know the 'nominal' voltage of 110/115/120 is both based on Vrms and
that stability @ any of those levels is pretty much a fairy tail.
Stability is not based on Vrms. Stability is determined by the ability of generators to maintain voltage despite fluctuating demand. Voltage is measured in Vrms. Utility companies usually comply with their specified voltage with ±10%. It's not a fairy tail. It's a requirement.
I also know that most rectifiers will output ~130-150V after
re-assembling the waveform & filling a comditioning cap.
A full-wave bridge rectifier will give out a peak DC voltage of \$ \sqrt 2 \cdot V_{RMS} - 2 ~diode~drops \$ (typically 0.7 V each).
I never heard of a 'conditioning' cap. The smoothing cap will maintain the DC output at peak DC voltage on no load but voltage will droop between peaks depending on load.
What I'm not 100% sure on, and don't really feel like digging out my
soldering iron & finding a few diodes to test it today, is the
peak-to-peak voltage of just the 'hot' 110VAC line. I.E. Will the
circuit below have ~130-150V, or ~260-300V across the + and - output
pins?
simulate this circuit – Schematic created using CircuitLab
Figures 1 and 2 based on original question, "Why is there no voltage reading between Probe+ and Probe-?".
Your circuit will have 0 V between Probe+ and Probe- as there is nothing to induce a potential difference between the probes. Even if you connect NODE2 to mains it just bounces the whole circuit up and down with respect to ground or neutral but still does not induce any potential difference between the two probes.
Edit after OP edit including deletion of the original wonky schematic:
What I'm not 100% sure on, and don't really feel like digging out my
soldering iron & finding a few diodes to test it today, is the
peak-to-peak voltage of the 110VAC 'hot' line.
\$ V_{P-P} = 2 \sqrt 2 \cdot V_{RMS} = 2 \sqrt 2 \cdot 110 = 311~V\$
Your diodes and capacitor are now irrelevant to this question unless you intended this:
simulate this circuit
Figure 2. Positive and negative rails generated by half-wave rectifiers.
This circuit will give you the peak to peak voltage of the mains between the two probes.