Though there are tons of places to be in Guwahati, but my personal favourites are :' Umananda Temple - A small river island with a hindu Temple and alot of friendly Monkeys. Fancy Bazar - It's one of the biggest market in Guwahati, if you want to buy local then this is it Hope this helps :)
Have a wonderful trip ahead Megha !
You already have a lot of suggestions, you should make a trip to chandubi lake outside the city. You can also get a glimpse of migratory birds during winter. Its a bird paradise, also fishing and camping is available.