My sister lives in Ft. Myers so for the past 5 April’s (soon to be 6) we have gone for 10days.
I have always loved the Gulf side, I feel like it’s more homey, granted some of the Naples/Marco Island, etc... areas are extravagant! But generally I feel it is laid back with all the retirees!
I can’t help with hotels since we stay at her house and drive to the beaches in the area. Sanibel has some places I would think of staying at but I have never looked into them. The island is laid back and shouldn’t be crazy like it is up until Easter....or at least I hope this Easter as we go after. We finally rented bikes/used my sisters and rented a surrey (never again, I will sit on the beach with my mother). It’s nice and flat and easy to ride but again not in a surrey. I am not overly fond of the Sanibel beaches to spend the day there, I do like the public beach in captiva but you have to go early to get one of the coveted parking. Spots.
We generally have been going south to the beaches in Bonita and Naples but we *love* Manasota Key beach for its free parking and sharks tooth hunting (yes there are tons). My kids are tired of the beach but they love going there. So I would also look into Sarasota/englewood/Venice for places to stay. You can either fly into tampa for Ft. Myers.
Free/cheap: there is always a mini golf course, a pier where there are fisherman catching stuff you don’t want to know you are swimming with (um, 2 baby sharks), shells galore.
I honestly think the water is much bluer north of Ft. Myers/Sanibel and the inlet/river that feeds into the gulf. It is also a hit or miss depending on the rain and tides.