I use bends and vibrato on a lot of my playing but not the flamboyant obvious guitar style, just a subtle amount that sounds more like a thickening than an obvious bend or vibrato. It's probably done like that on a lot more recordings than you realise. Often when people ask how to EQ their amp for a particular "fat" tone this is what they really want.
That's a nice idea. Listening to some of my own recordings I hear slight bends that sound good, others bad, they're just enough to add a textural detail rather than an obvious pitch change. Slow or slight vibrato to continue it might be viable, easy enough if I practise it. Could be a great sound if using delays, chorus, rather than using the inherent modulation in most chorus effects. (I extended a software synth I wrote to allow similar subtle pitch changes. Mechanical detunes are never enough, cool though they can be..)
Mind you, I like to forge ahead in a punk/metal inspired sort of way with a bass, I like fast melodic moments to keep things interesting, and a lot of the time I use the bass percussively, (but not like slap bass, can't do it). When I want to avoid an ear-bashing I put down a pick and play sea songs, folk tunes, Andean tunes, lots of stuff that could well use methods I wouldn't use when banging away with a pick. I'm just getting good enough to start thinking about this more..
@Wasnex, I like to do small gracenote legatos at times, I picked that up from mtal and rock I liked at times various. Sometimes it's so short it's almost a rhythmic device rather than a pitched thing. Also, heading closer to topic, I like your method of lines as markers on manuscript. I am lousy at reading music but to learn a song I'll often open in Sound Forge, filter heavily, drop markers to subdivide phrases, bars, so I hear various units of construction so I can figure out complex bass parts. I image this method would work well on the unfiltered sound to examine how a vocal overlays a bass part. It would be harder to drop markers with any precision but they can be moved to get some chance of hearing a small part without distractions. I like the Sound Forge controls, they make auditioning, repeating, very fast and easy so at least I don't have to think about that when I do it. It's a very musical editor in that way, not poky, it's good when my hand remembers the moves so my brain doesn't have to, same as with an instrument. I recommend this method to anyone who can't read music, if they have a recording of a song they want to learn.