When I sit in at my friend's blues jam, I don't mind doing an expressive one for a chorus, maybe two(although at that point I'm looking at the drummer for his stink-eye of disapproval). The only two long ones that I think were valid were on upright and in jazz...
I'm sure there's more that I haven't heard, but overall I like to stick with the KISS credo, 'keep it simple, stupid", or else it will go something like this...
A man goes on a vacation to a tropical island. As soon as the plane lands, he gets off and hears drumming. At first, he thinks, “This is pretty cool”. He ends up going to a luau and hears the drumming. He eats lunch and hears the drums. He goes to the beach and hears the drums. He tries to sleep, but can’t because of the constant drumming.
The drumming goes on for four days. The guy has to go down to the front desk because he can’t sleep. He asks the manager “What is the deal with these drums! Make them stop. I haven’t got any sleep this whole week!”
The manager of the hotel says “No. Drums don’t stop. You don’t want the drums to stop, sir.”
“Why?”
“Because when drums stop… Bass solo begins!”
Anywaaaay.....
What I enjoy the most, playing or listening to, are brief showcasing 'breakdowns', just get in and get out to remind the audience that you're there, and not belabor the point. Like JPJ's two moments in Zep's "Good Times Bad Times", or one of my favorites from early Blue Oyster Cult(at 3:03)...
(every time I go see Mike Watt play, he trots out a cover of this)
or this intro, which is not exactly a naked bass line setting up the groove like "We Gotta Get Out Of This Place", "Badge", "Lost Woman" or "Billy Jean"...
or the slow burn 'solo within a song' here at 1:32...
which is a slight homage to this breakdown(at 3:05)...
Because at the end of the day, the sad truth is nobody in the audience(besides your significant other)cares how awesome you are.