Check out this website - it gives you info on all restaurants in Portland.
http://www.portlandfoodmap.com/
For lobster rolls in town - you can try any of the places on Commercial St in the Old Port. For fish go to Street and Co on Wharf St. Fore Street is good wood grilled local food. Caiola's in the West Ends is Great!! For drinks go to Grace - a great grand space in an old church.
Upscale Mexican - El Rayo Cantino -
http://www.elrayocantina.com/menu
Upscale Comfort Food - Caiola's -http://caiolas.com/
Fore Street -
http://www.forestreet.biz/
Paninis and the best fries you will ever eat - Duck Fat -
http://duckfat.com/
Sushi and Japanese - Miyake -
http://www.miyakerestaurants.com/miyake/
Italian - Bresca -
http://restaurantbresca.com/
Upscale greek - Emilitsa -
http://emilitsa.com/
German - Schulte & Herr -
http://schulteundherr.wordpress.com/
Fish - Street & Co. -
http://www.streetandcompany.net/
Cocktails - Grace -
http://www.restaurantgrace.com/
Great food with a Spanish influence - Sonny's -
http://www.sonnysportland.com/