Yes, there are as many shells as the rumors say...but be prepared to shell out the dough too ($6 toll and $4 an hour to park).
Sanibel is gorgeous.
There are many easy to access, beautiful beaches, and a good variety of shells. The visitors center was very helpful, and the free shell guide not only showed us what to look for and what they were, but also had a guide for caring for the shells you find.
We were only to be in the area for one day, so we decided to make the most of it. It turns out that the day we were there was to be a negative tide at 5:30 AM. And as we learned in Alaska...if there is a negative tide...you go. Amazing things will be found. So we dragged our booties out of bed at 4:15 to make sure we were there in time.
With flashlights and headlamps and blankets (it was chilly!) and baskets we set out. We spent about 2 hours at the first beach (Lighthouse Beach, touted by many as the best for shelling...and it did not disappoint,) before deciding to warm up at a local coffee shop. After that we did a quick driving tour of both Sanibel and Captiva Islands. Then we headed back to Sanibel for beach number two. We spent about an hour here, and then feeling tired and needing to go potty we decided to take a break.
We headed over to the Bailey-Matthews National Shell Museum...located on beautiful Sanibel Island. We ended up spending about two hours looking through their collection, watching documentaries and listening to a marine biologist give a talk.
After that we headed back to yet another beach, this one was much better suited for playing. So we spent another hour or so playing in the surf, tossing a football, and just hanging out on the beach. By then we were pretty wiped out, and the kids were excited to go back and look through all the shells they found.
It was just one of those really good days.