On my way to do other things, I noticed an awfully good rate on some Ruby Princess sailings out of Galveston. I'm attaching screenshots of the best one for a cruise in late February, but I tested one from April that was nearly as good.
Notes:
This is for an obstructed OV, which I found in the interior section. Plenty of availability in this class of cabin on this date.
Rates go up for true OVs through mini-suites, though probably not as much as you might think.
UPDATE: In continued research on this fare, I found that it's also available from certain sailings from Fort Lauderdale on the Regal, Sky, and Caribbean. I was on the Regal a year ago; it's a nice ship. The cruise fares are a bit higher, as are the port fees, but there's still no single tax. Here's a screen shot of one of the better sailings I could find in an obstructed OV in April on the Caribbean Princess:
Here's how to quickly find them in your search on princess.com: