Manali is a great place to go with family. There are hundreds of hotels. So dont worry about hotel booking. You can get a family room for 600 to 800. Try to stay at Mall road if you like crowd and all happening of Manali. But beware of pick pocketers.
When you go to Manali you must see Rotang Pass and Jharna falls. These are most memorable experiences. Also spend time on river side in the garden. Rafting is another must for every one. It should cost not more than Rs.1200 for 3 persons for 14 kilometer rafting. While going to Rotang pass, dont be in hurry to hire the costumes. They will be there on the road for more than 5 kilometer stretch. The Car driver may misguide you to hire it from a shop owner where he could get commission. Instead travel for 5 kilometers and hire it from a shop while you about to climb the hills. Insist for bright colors. Skiing cost he may ask for 1500 but you can get it at 800. You can also get it on hill top. So dont worry.
Visit Vashisht kund. You can visit all local sites in Auto rickshaw. It cost Rs.300 and takes one whole day. Stay for atleast 3 days to see all. We visited in May end. The weather is pleasant. But for better snowfall you should go from december to Jan.
You get all types of food. but having their local dishes is great. Food at Jharna water fall is the best. You must try something new there. Food at Tourism hotel at Mall road "Bittu" is great to have. Try himachali food. Never buy Badaam on road side. It is not good.
Going from Chandigarh is best. From Delhi it is difficult journey. But the bus root is also adventurous. Bus from Delhi cost about 300 per head for non A/c sleeper coach.