I'd certainly check on red tide problems. We've been to Daytona, and it was okay. We had a decent hotel right on the beach, so that made it decent, but some parts of the area weren't all that nice, but lots of places to eat.
In Florida, if you don't love what you see at a certain beach, just a little north or south and you'll find another beach.
That time of year I'd say east coast FL water is enjoyable, maybe even a little warm compared to more northern east coast beaches. Folks go swimming all the way up the east coast.
On the gulf side, we really liked some of the smaller beaches near Clearwater. Clearwater itself is built up, but Honeymoon Island Park is very pretty, natural, and inexpensive. We also found a little beach called Indian Rocks. There's a parking area with low fees, shade, a bathhouse, and across the street is a fabulous place to eat called Guppies! We never made it south of Indian Rocks, but a local said there were very nice beaches further south.
East coast has bigger waves, so we tend to wave hop instead of swimming. Gulf side has softer sand, more pretty shells, but less waves. Better for swimming, but you don't get as much of the sound of the waves. Honeymoon Island did have critters, but we didn't see anything unpleasant. We saw osprey, and an owl. Though there were signs posted for snakes and sting rays.
Oh, also know October is still the tail end of hurricane season. Low odds of a storm impacting you, but just know they CAN happen that late.
