I will be in Nashua for a week house hunting, are there any restaurants and/or sights, gardens I should make time for? I like local places plain or fancy; and love older things (buildings, music, culture)
Saint Gaudens in Cornish is a bit of a drive but well worth it. Keene has a nice downtown and is a college town. You might consider a day in Boston which is a really nice city - obviously lots of history there. All are a bit out of the way, but depending on your spare time... Those would be my suggestions!
When are you coming? Are you looking for places strictly in or very nearby Nashua or are you hoping to get out and explore? Keene is probably 1:15 from Nashua and I imagine St Gaudens is even farther.
In Nashua or nearby: For a nicer restaurant there is Surf right on Main Street (if you like seafood of course). The owner of Surf also own's MT's Local Kitchen & Winebar. Never been but if it is as well done as Surf it is probably pretty good. There is also Peddler's Daughter if you are looking for a noisy Irish Pub.
Just a little ways North of Nashua in Merrimack is The Common Man. This is not a chain but there are about a half dozen around the state. It is locally owned and considered by many to be a very NH experience. I think the food is good (comfort foods) but I also like the homey atmosphere.
Just a town or two West of Nashua is Mason. Two places to check out. Pickity Place and Parker's Maple Barn. Pickity Place was the model for Grandmother's House in the original Little Red Riding Hood illustrated book. It is more than just a house to see. It is a destination for gardeners and foodies alike with its gardens and greenhouses and beautiful grounds to walk. They do a price fixe lunch and you often need advanced reservations for a table. Really great place! Parker's Maple Barn can best be described as an authentic Cracker Barrel. Excellent breakfast place (also open for lunch) and its a working maple sugar house as well.
Mason is also home to the original Uncle Sam and I believe you can tour his home. There is also a nice walking trail just East of Parkers by about a mile at the junction of Rt 13.
Also nearby Nashua is Brookline which is home to the Andres Institute of Art. You can walk the grounds and see the sculptures. I personally have never been and suspect wpsaukee might be able to give you more details but I have heard it is very nice.
Peterborough is about 45 minutes from Nashua (depending on where in Nashua you will be). Its a quintessential pedestrian friendly New England town with a thriving downtown retail and dining scene. Lots of suggestions here but I mention it because you could go to Miller State Park nearby. It has an auto road you can drive to the peak (depending on when you are coming) and you could get beautiful views of the surrounding countryside (can see the Boston skyline on a clear day).
That's a few ideas...I have a lot more and I know others will have great suggestions. If I knew how far you wanted to go I could throw a few more ideas out there.
Riverwalk also has great music at night, many nights of the week. Everything from Bluegrass to jazz.
Both Surf and MT's are excellent, as is a third restaurant owned by the same guy, Buckley's Great Steaks in Merrimack.
Nashua Garden is a popular bar/sandwich place; Martha's Exchange is a nice brew pub with good food and a dangerous candy shop.
The League of NH Craftsmen shop has beautiful locally hand-crafted items.
All of the above with the exception of Buckley's are on Main Street within easy walking distance of each other. Also within walking distance, but on Temple Street a couple of blocks east of Main, check out Collins Brothers Chowder Company for great chowder and other soups in an environment that looks and feels like the 1950's. Check their hours, though (http://www.collinsbrotherschowder.com/)--they're closed Sun-Tues, and it's just a take-out place catering to the lunch crowd.