Often underestimated for its contribution to the tone, resonant heads are mostly responsible for the pitch, lingering tone and pitch of that created as a result of striking the batter head and resonance of the shell. Since the resonant head produces “resonance” and aids in sustain, it has a major effect in the overtones and enhances the timbre of the drum. Generally, you do not use anything other than single ply (Ambassador, G1, etc.) on the bottom, but there are exceptions.
Basically, your Ambassador-weight resonant head is a good middle ground in terms of sustain, resonance, and pitch. Any thinner (less mass = less energy = less sustain) or thicker (too much mass = less energy = less sustain), you lose sustain, resonance, and deaden the drum sound.
For snare side reso heads, there are a lot of options...the industry standard again, is the Ambassador (hazy). You can go with a Diplomat (thinner) for increased sensitivity and snare response, or thicker for a deader, boxier sound.