Hi qh89,
I proudly own a NG-2 of the newer series, with the rounded pickups.
The settings I use most:
middle pickup only: I swear, the best sounding P-tone ever. It took me a bit to figure out the EQing and amp settings, but this is now my go-to setting for just about everything "normal" like acoustic sessions or pocket playing... but also aggressive pick style stuff. The definite number one.
both pickups parallel: whenever I need funky or punchy tone, I play this setting. Rage against the machine style heavy fingerpicking. It sounds very direct, MM like. Can definitely cover the same styles. It is missing the distinct Stingray grunt though. Still I could not live without that setting.
both in Series: rarely use it. My setting for overdriven sounds and heavier style. The abrasive and cutting mids work very well in a busy and heavy mix.
I don't use the bridge PU solo at all.
Also, I've experimented with moving the middle pickup to the neck position. So I also know the jazz bass setting and neck pu only. After hearing the great middle pickup solo I was looking forward to the neck only, but it just doesn't compare somehow. The jazz setting (neck and bridge in parallel) is great, has the best sound for just noodling around. That's the best sounding tone setting imo, but it's not that usable in the kind of mixes that I play in.