Places to stay (and things to do) in Portland
Hotel options
Hampton Inn (Waterfront) is a few blocks from the CBITD ferry terminal and within walking distance of all the Old Port shops (as well as the ferry terminal) but it's ~$500 a night.
Hampton Inn (West) is a drive from downtown Portland but is ~$250 a night.
AirBnB has a few options in Portland (and as of writing this, one on Peaks) at varying levels of affordability.
Things to do in Portland
Walk around anywhere between Commercial and Congress streets to experience the Old Port, which has lots of nice shops and restaurants.
Harbor Fish Market is a must if you're in the Old Port.
Fish Point is a ~20 minute walk from the ferry terminal and gives you a nice view of Casco Bay.
Places to eat in Portland
Holy Donut sells potato donuts. They are very very good.
Standard Baking sells pastries and things just a block from the ferry terminal.
Flatbread Company is a perfect place for lunch. Amazing pizza and right next to the ferry terminal.
Fore Street for a really fancy dinner, go here (with a reservation).