Haven't been to the Clearwater Marine Aquarium yet. I hear it's just a little place, but a lot of fun (something you can do pretty quickly -- maybe two or three hours). They have a shuttle and another site too with some Winter movie stuff. People enjoy it, but say don't expect Sea World. Trip Advisor has over 150 people who have posted reveiws if you want to read some and hear some first hand reports.
Normal admission price is something like $18 for adults, so way less than an Orlando theme park
For my mini budget trip this June (two nights in Clearwater before I drop DS off at the Busch Gardens 101 camp in Tampa for High School students, I picked Sea Captain Resort. My cousin who lives in Tampa is going to stay with us too. It appears that this is right by Pier 60 and the great public beach and lots of resturants which is what I wanted (wanted to be able to walk right over). We grabbed one of their suites to get a full kitchette. It looks more like a clean family run place than a fancy resort, but should work fine for us for two nights and fits in my little mini budget for this. And the location is just what I wanted.// I actually got two free tickets to the Marine Aquarium due to my mentioning a web site that I saw Sea Captain Resort listed on as a Marine Aquarium preferred property (I don't remember the exact details, but I always like getting freebies thrown in). They sell marginally discounted tickets too, so we'll use them to get our other tickets too.
Most people post an hour and a half drive time, but it usually takes me a good two hours to get from my resort in Orlando to Clearwater Beach. Clearwater is a great beach, though, and my favorite for a day trip from Orlando. // On this little trip, though, I'll just be flying into Tampa and won't even go to Orlando.