Go to Inn at Swan River in West Dennis - Mid Cape. Beautiful Inn with 26 suites w/kitchenettes, outdoor heated pool, fire pit, bbq grill w/picnic area and just one mile to uncluttered beach!
Definitely take some time to walk around the mall. It's quite large, but I'd recommend heading over in the direction of the capitol, or going over to the Lincoln Memorial and Vietnam Memorial area.
If you haven't seen the water show up close, it's definitely worth slotting some time for. Seeing pictures or video doesn't convey the magnitude of the show.