weather in November for Krabi will be best time for you to visit.... as the monsoon period will be from September-october.... The most busy place in Krabi would be Ao Nang area...
Below are some suggeston for the sites you can go for a visit or activity to do:
You can visit the world famous Phi Phi island group, as well as several smaller islands close to the shore. The imposing karst scenery of Phang Nga Bay, to the north of Krabi, is also well worth.
North of Ao Nang there are several deserted tidal beaches, such as Haad Noppharat Thara; which you can have all to yourself (its also ideal for early morning jogs and you can run there easily from Ao Nang). South of Ao Nang is the Phra Nang Cape (where Railay beach is located) and once rounding this you enter Nam Mao Bay.
From Krabi Town, tours of the Krabi River estuary are popular and offer a different side to the usual towering landscapes that are typical of this region. There is a surprising amount of interesting flora and fauna found here and the tidal changes offer different perspectives. Early morning or sunset tours on longtail boats from the city waterfront pier are best. If you’ve rented a bike for the day you might wish to leave the coast altogether and seek out the unusual Wat Tam Sueu (Tiger Cave temple), which is south of Krabi Town.
The complex is comprised of a caved sanctuary at the base of a towering karst pillar, plus an exhausting 1,200-step climb to view a massive Buddha statue and chedi on top. The panoramic view of the surrounding area is also spectacular. It is an active and famous forest retreat temple and is home to a troupe of thieving monkeys, so keep valuables concealed. Also worth visiting is Than Bokkharani National Park, 20 minutes drive north of Ao Nang in the Ao Luek area. It’s a delightful fairytale landscape of emerald pools cascading into streams, along with plenty of caves and karst topography.
Hope this help you some !!