I am here on work and have a free weekend in which I would like to go to Niagara falls. I dont have driving license, so can not rent a car and drive. Can someone suggest a way to visit Niagara falls from gaithersburg, MD ?
I have explored and found that one route possible is thorugh air. Is there any other option apart from taking flight from DC to Buffalo, NY ?

Possibly bus or Amtrak.

Bus or train would take a very long time, though

IMO air travel is the only way to go for a weekend trip. Check out Priceline packages. Not knowing what weekend you wanted I just plugged in any weekends dates and came up with this: http://tinyurl.com/dzzld3
Of the first three hotels that are listed there, I can recommend the Marriott. It has wonderful Falls views and close enought to walk everywhere or take a shuttle. The third one on that list is the Sheraton and also good. Whatever you decide, stay on the Canadian side and choose a hotel that is close to the Falls so that it is walkable. You might have better pricing by not chosing a package. Just to sucure your airfare and then your hotel. If that is the case, I would recommend Embassy Suites. They give a great package of two nights (or one night) that includes a great breakfast and $40 off dinner in their Keg restaurant where you can have a window seat overlooking the Falls. (the Marriott is right next door BTW, great location for both hotels)
http://www.embassysuitesniagara.com/

Let us know what you decide. Have fun!

It is a good walking area (one of the best) There is good transportation by bus and Amtrak......

I have a friend who was flying to Buffalo Airport and wanted to get to Niagara cheaply--that cannot be done. Good to go an all bus or all train route.

Happy Travels !!