It all depends on whether or not you working with what you have or creating a system.
Not all amps can be bridged, that said, if you are starting from scratch why not match the amp and speakers to begin with?
Scan through my build thread, you'll see what I'm doing with my front speakers and rear, rears will be treated as mid-bass.
Tweeters are in the sail panels, not the dash, not the door card.
I had a moment of stupidity some time back, I cheaped out on the sub, thinking that I was going to use the 5 channel amp I already had. Existing amp and sub are by the wayside now.
New sub will be as shown here, new amp will most definitely also be JL, I have not decided on 4 or 6 channel, sub is active.
Active or passive crossovers.........that's my question to resolve but is some time off yet.
What head unit? what amp? what speakers? crossovers? staging? wiring? sound control/vibration/deadening....what are you doing about that, the MJ is a F-ing rattle-trap?