I don't know how much I'd personally derive from toting around full saddle bags. For me, it would limit the spontaneity that I'm looking for.
I really don't understand how it would limit your spontaneity to have a couple of panniers.
And I agree with a few other people here--in my experience, people are way more likely to offer you hospitality when it's obvious you're a cyclist on tour, and nothing screams "I'm touring!" like panniers.