i've lived in Quincy (next door to Boston) for 30 years and sadly i can't even really recommend a place. i'm not saying there aren't great places, there are dozens, "a night out on the town" isn't my expertise though. i'm better off in a shitty bar with buffalo wings. however, people really like:
Grill23 -
http://www.grill23.com - not sure if this is as "high class" as you're looking for
KO Prime -
http://www.koprimeboston.com - people have been hyping this place up a bit
really before i just list off places there's too many to, i guess decide on exactly what kind of food you want and search that way. the north end alone probably has 50 great places, or even more. actually the gf & i are trying to decide on a place in the north end for saturday night and even that is overwhelming. good luck and have fun though. if you like italian focus on the north end.
good call Sath, top of the hub might be exactly what they are looking for. not my thing but for a place to get all dressed up and see what you are usually missing that sounds like the spot.