Don't bother staying in Flores while visiting Tikal
El Remate and the surrounding ares by the north shore of the lake is the place to be.
the town is quiet, charming and closer to the national park. I stayed in the cute Posada Del Cerro. On your down time (when not in the park) you can swim in the lake or hike next door in the Biotopo Cerro Cahui preserve. Its hot and wet in the part of Guatemala - and was once a huge lush jungle. You can still see remnants of that as you explore.
There are simple but lovely bungalows spread throughout Posada Del Cerro. The foods is not great but there are plenty of other establishments that dot the lakeshore.