Very easy, whuch is helpful since I'm a lowly guitarist not quite as far along the evolutionary trail as most bassists.(That's a joke
)
Well said!
Your initial post is a bit complicated, since you're asking what WE'D bring, in order to find out what YOU should buy, to use yourself.
Yes, the music might require versatility, and I personally own these, in order to cover all session bases (no pun intended):
Fender P with rounds
Fender P with flats
Fender P with added J pickup, defretted, with halfrounds
Fender Jazz with rounds
Fender Jazz with flats
Music Man Stingray 5-string with rounds
However, I chose to answer the part of your question regarding what one bass you, a lowly guitarist
Hence, I still suggest a P Bass.
You really don't need a Fender P Bass, either.
I've also used an old Univox P Bass copy, and even an SX P Bass copy, with great results. As long as it's set up well (no fret buzz, correct intonation) and electronically sound (no hum, no crackle) you're fine.
(That's a joke