My parents used to live in Tierra Verde (last exit off of Pinellas Bayway before St Pete Beach) and I always wanted to go stay/dine at the Don Cesar. There were also some decent spots in Pass-A-Grill, just south of there, which were nice for food/drinks/sunset. Not sure if it's the same nowadays, but it's either Brass Monkey or Paradise Grill that we used to frequent. I also remember several good meals at Billy's Stone Crab in Tierra Verde. Sadly, many of the other places we frequented are gone. Some of them were John's Pass/Madeira Beach area, but I can't find them on the map.
We also really liked visiting the St. Pete Pier. I haven't been since they got rid of the inverted pyramid, but it was always a nice place to go for a little while.
I guess if you're into pink hotels, there's also the Vinoy. When my parents first moved to that part of FL, they were renting a home that was closer to that one.
If you're a fan of art/Dali, The Dali is phenomenal. No guarantees, but we've often seen manatees in the water areas near the museum.
Not sure how you feel about zoos or driving into Tampa, but ZooTampa at Lowry Park is an amazing zoo. It's been some time since I've been, but I know they've put in a ton of upgrades and it's considered top tier in the zoo world.
Back in the St. Pete Beach/Tierra Verde area, you could always take a drive down to Fort DeSoto. That was another spot we used to visit quite a bit.
The last thing I can think of is heading over to the Sunshine Skyway. We often would stop at the little Skyway beaches on either side of the bridge.
They moved from that part of FL to the Ft. Lauderdale area about 20 years ago, but I really liked when they lived in that part of the state.