Front: Poly bushings are good, delrin bushings are better
Tubular lower A-arms - they all keep the exact same geometry, and most weigh about the same as stock arms, so you're not shedding much, if any unsprung weight. The only advantage tubular arms will get you is added strength, and they look cool. You can box your lowers for far less to make up for any strength concerns.
Tubular upper A-arms - There are a lot of options for these, from the $49 circle-track arms that are built very light to the beefy $569 GW arms with delrin bushings. They all do 1 thing - they are shorter to allow for a taller spindle. I prefer the SPC adjustable arms from SC&C for $269. I plan to use them to get the car aligned, then lock in the lengths and use shims to make an easy to reproduce "track" alignment setting.
Spindles - read this
http://www.chevelles.com/forums/showthread.php?t=107745 I think I covered all the popular spindle swaps. The best options available out there are the stock spindle with tall ball-joints from SC&C, the tall drop spindle from Fatman, and the AFX spindle from ATS... I think the tall ball joints are the only ones currently available though.
Rear: Poly is bad, Delrin is WORSE. Rubber is good, and spherical rod-ends are better.
If you want a cushy ride, stick with rubber uppers in your stock upper arms
If you're more concerned about handling, go with something like
Wolfe Racecraft arms with spherical ends, and their spherical bearing for the housing.