I can safely say the most relaxing thing I did in January was lie on the floor and watch sharks and stingrays pass overhead.
A winter weekday is probably the best day to visit the Newport Aquarium—no crowds, more personalized attention from the aquarium staff, and less noise make this a worthwhile spend. My guest and I made sure we caught certain highlights, namely the sea otter feeding, and we browsed every corner of this meticulously managed facility (save an escaped field mouse—some reptile's dinner gone rogue).
I recommend paying the extra $25 for a personal visit with the penguins. The shoe- and dangling-strap-obsessed, chubby little birds provided a great deal of entertainment. You get a chance to pet one and have your picture taken with her (all of the penguins in their posse are female).
Besides the otter feeding (and splashing and diving and teeth-brushing) and the penguin visit, we enjoyed the frog collection, the general penguin exhibit (lots of impressive waddling, speed swimming, and launching up out of the water), and the jellyfish lounge. (Really, my life would be complete if I could host a cocktail party in that room full of lazily floating, luminescent blobs.)
If you get hungry walk over to the Hofbräuhaus Newport for beer and brats, then wander back in for more aquarium fun. Make sure you watch the sun set over the Ohio River as it presents a beautiful silhouette of the Taylor-Southgate Bridge, all while the Cincinnati skyline begins to sparkle.