Thank you all for your feedback.
My gal got word of a "deal" on Carnival Spirit, leaving San Diego on 12 October and returning 5 days later. That pretty closely matches our needs, departure and return locations, and price estimates so we went ahead and committed to it.
We did this sort of "blind" as you're able to assess from the short amount of time since my first post here. I'm nervous that we did the right thing, but hopeful as well.
Next time - assuming this all works out as we're hoping - we'll plan further ahead.
Here's to hoping that our first time is charmed...