WOW.....we were at Southseas Resort for 3 weeks last December (one of our longest vacations in one location). It was cooler some days than we expected so make sure you do at least bring a couple long sleeves/light jacket. (you can read my review at Plantation Beach). We were isolating so I can't provide any info on group activities....husband fished, we road bikes, read, explored, collected tons of shells; The pool was warm enough to swim. We found the two grocery stores on the island (Sanibel) to be really good...they're full service (and the one will provide delivery to your condo, if you prefer). I'm sure you can get Amazon delivery for anything (we just had amazon deliver at Hilton Head and we were only there for a week). We didn't pack for 3 weeks, we just added weeks as they became available and we drove (are you flying and renting a car?.....you will need a car) . We found PLENTY to do and the time actually passed quickly! We very much enjoyed having extra time to explore & not feeling "rushed" to get everything done in a typical 1 week. Honestly I wouldn't have had time for much indoor activity/hobbies because I loved being outside and just "being" at the beach (even at 3 weeks) & books don't take up much room. If you have any specific questions....ask.