Modifying Philharmonic 3 crossovers

How about one type of caps for the tweeter and one type for midrange?

I'd recommend all series caps be the same.

Because parallel caps are not directly in line, and often much larger and more expensive, that is where you may want to do some cost savings.

What I'd recommend for instance is to use Clarity CMR for the series, and ESA or CSA caps for the parallel. 
Imagine the expense if you had gone with all Jupiter copper foil! :)

Hi Erik, I already purchased an 100uf clarity CSA capacitor to replace a Solen fast capacitor of the same farad rating for the bass. I just now ordered two 20uf clarity CMR capacitors to replace two clarity PX capacitors of the same rating for the mid. I also just now purchased a clarity CMR 3.3uf and 5.6uf capacitors to replace two clarity PX capacitors of the same rating for the highs. I was wondering about something though, there is a Solen 50uf capacitor that connects to both the two 20uf caps in serial and the 3.3/5.6 in serial. I want to replace the solen 50uf with another CMR capacitor although there aren't any 50uf CMRs. Would placing a 15/15/20uf capacitors in parallel be ok? Lol, I know, purchasing a 50uf clarity CSA would be a lot easier(and cheaper) although I'd like to keep it all CMRs, except for the bass(100uf CSA). What is your suggestion?

Yes, parallel caps add.

Thanks Erik for your help so far in choosing capacitor. Right now I'm getting all the new Clarity CMRs setup in the crossover and I was wondering about resistors. I looked at Duelund cast resistors because they're not as terribly expensive as their capacitors, although I noticed people saying that it sounds bright(and it uses silver) so I think I'll stay away from those. I heard really good reviews from audio path, vishay, audio note and mills, although I'm not entirely sure which to choose. What I want from the resistors I'm going to buy is for them to be as neutral/natural as possible with lots of resolution & dynamics and won't add brightness/hardness to the sound. Do you have any suggestions Erik? Also, when going through the forums I always see people talking about bypassing with certain caps(ie. jupiter). What do they mean?

Resistors: Mills
Inexpensive, very good, dead accurate and thermally stable. I'm not a fan of Duelund's as they are deliberately not thermally stable. No thank you. :)

As for bypassing,that's what I was discussing with CMR caps above 5 uF. Use a 0.1uF jupiter or Audyn TrueCopper ($20) to bypass them, in other words, put in parallel with the main cap.

What I do while testing is I use alligator clips to attach the Audyn where I think it may make a difference and listen.