Wa alaykum as-salam,
The children of Muslims go to Paradise according to the hadith: "A Muslim parent will not lose three children who did not reach the age where one is held to one's word except Allah will cause him/her to enter Paradise because of his/her love for them." Bukhari and others. Ibn Hajar in Fath al-Bari specified that the children themselves will be waiting at the gates, opening them for their parents as narrated in similar versions by Ibn Majah (hasan) and al-Nasa'i (sahih) in their Sunan. See al-Suyuti's monograph Bard al-Akbad `an Faqd al-Awlad ("Consolation at the Loss of One's Children"), ed. `Abd al-Jalil al-`Ata (Damascus, 1992).
There are nine views or more on the issue of the children of non-Muslims. The safest view is that of Imam al-Shafi`i -- may Allah be well-pleased with him -- whereby they are entirely dependent on Allah's will for them due to the hadith: "... When Allah created them he knew best what they would have done [if they had lived]" (Bukhari, Muslim and others). Another strong view is that they are in Paradise because Allah said: "We do not punish until after we send a Messenger" and other evidence. And Allah knows best.
GF Haddad Qasyoun@cyberia.net.lb