Is my miqat for ihram for Hajj the miqat of the people of Makkah, so I should enter into ihram from my home, or the miqat of the people of Riyadh, so I should enter into ihram from Al-Sail, knowing that I reside in Makkah and my family resides there, while I work in Riyadh and return to them monthly and during holidays?

For whoever leaves Mecca to go beyond the Miqats for a need, then passes by one of them intending to perform a ritual (Hajj or Umrah (definition)), it is obligatory for him to enter into a state of Ihram (definition) from the Miqat (definition). This is due to the generality of the Prophet’s (peace and blessings be upon him) statement regarding the Miqats: "They are for them and for whoever comes upon them from other than their people, intending Hajj or Umrah." As for someone who passes by the Miqat without intending to perform a ritual, Ihram is not obligatory upon him. If he later forms the intention for a ritual, he may enter into Ihram from where he formed the intention. If a Meccan enters into Ihram for Hajj as a Mutamatti' or a Qiran (definition), no sacrifice (Dam) is required of him.