I haven't stayed at the Hilton, but I stayed at the Holiday Inn a few years back and loved Longboat Key. The HI was also great with a huge indoor covered atrium with a pool, hottub, games etc.... They have kidsuites so the kids had their own "room" in the back of our room. There is also lots to do in that area, we thought, though we mostly enjoyed the beach. It was my first time staying on the gulf - I've always done my beach trips on the Atlantic coast and it was great with kids - very, very calm. Longboat key is next to St. Armands key which has a main business area called St. Armand's Circle that's kind of a big traffic circle with shops and restaurants all the way around. In Sarasota we went to the Ringling Museum which I highly recommend. There is a huge art museum and a separate circus museum and the Ca'd Zan which is on the water and was recently renovated (while we were there - so we only saw the outside. There's even a nice restaurant there for lunch. The day we were there they actually had a circus performance that you could attend at no extra charge in the small Circus museum. The kids were sitting right on the floor in front of the performers and there was exceptional interaction. One mime kept throwing his hat at my husband to get him to throw it back on his head - after many, many tries, he got it on there. Awesome! My husband also enjoyed visiting some old bookstores while I got to take oldest son to a doctor where he was diagnosed with strep and bronchitis. Even that was a nice facility and right on Longboat Key and whatever they prescribed had him well the next day. Thre is also the Mote Marine aquarium that we just didn't have time for (plus it was REALLY hot in August.)
As you can tell, I can't say enough!