Selby Botanical Gardens is a really nice place to visit. They have a pretty big diversity of plants and you can spend an entire day here if you wanted. We've been a couple of times and usually after about 4 hours we've had enough which is saying quite a bit, since for us 4 hours is enough time to do either Busch Gardens or Sea World! The price is very good ~$10, and occasionally they'll have free admission.
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