Seats near the dugout would be great too.
There are a bunch of great places to eat. The North End is filled with awesome Italian food and pizza. Chinatown is ok, but nothing special. There are a ton of places on Boylston/Newbury St that you could check out (burgers/pizza/American fare). Lots of good Indian food as well. Not too many worthwhile TexMex spots though. I'd skip all the burrito joints too.
People typically grab a duck tour, walk the freedom trail, go to Harvard Sq, go shopping on Newbury, Fanueil Hall (sp?), go to the aquarium and other touristy stuff. You'll have a lot more fun coming with another person unless you don't mind wandering around by yourself. Boston is a very walkable and fun to explore around by foot.
If I was going to show someone around, I'd do breakfast at Mike's Diner, wander around Newbury, walk to the Boston Public Gardens, do the freedom trail, get dinner in the North End and dessert at Mike's Pasteries (though there are better spots). The next day, I'd take the T out to Harvard Sq for lunch and shopping, walk down Mass ave through Central and back over the bridge, get dinner at the Pour House and ice cream at JP Licks. If you were 21+ (you aren't) I'd send you to some other spots too. The Fenway/Kenmore Sq area is ok to wander around, but it has lost a lot of the more fun stuff over the past 15 years.