If it is a good day out, I would recommend saltwater. We have a couple of charters in the area. Let me know if you need names and numbers. We also have a couple of shore dives:
Venice - some life but not really. This place is for collecting sharks teeth. Depth for teeth is about 17-20. Don't stop in spots that are just sand - look for areas with with rocks, shells, and what not. When you walk out onto the beach have a look back at the line of trees. You will see three tall palms, head out from there or head out from the large white culvert, your choice.
Directions: Google Maps
I-75 exit 200 to Osprey.
Continue Southeast on TAMIAMI TRL N/FL-45 S/US-41 S toward BAYVIEW DR. Continue to follow TAMIAMI TRL N/FL-45 S. 7.4 miles Map
Turn RIGHT onto MIAMI AVE W. <0.1 miles
Turn LEFT onto NOKOMIS AVE S. <0.1 miles
Turn RIGHT onto PONCE DE LEON AVE. 0.3 miles
Turn LEFT onto HARBOR DR S. 0.1 miles
Turn RIGHT onto ALHAMBRA RD. 0.4 miles
Follow ALHAMBRA RD to the end
Spanish Rocks at Anna Maria Island is a good dive as well. Here you will find some life. Also if you have an SO that is not a diver they will enjoy the beach here.
There is also the Regina/SugarBarge but I wouldn't even bother.