God gave David the house and kingdom of Saul and because Saul's wives were his property as well, they automatically came with the house and kingdom. It wasn't that God personally selected the women to be with David.
I am looking for scripture that says God wants David to have multiple wives because it is His will and a blessing.
OK, see now you're picking at hairs! The question originally was NOT about GOD selecting multiple wives, but GOD giving multiple wives. But since you asked, lets see exactly what the scriptures says:
2nd Samuel 12:7-8 "And Nathan said to David, Thou art the man. Thus saith the LORD God of Israel, I anointed thee king over Israel, and I delivered thee out of the hand of Saul; and I gave thee thy master's house, and thy master's wives into thy bosom, and gave thee the house of Israel and of Judah; and if that had been too little, I would moreover have given unto thee such and such things."
GOD gave them to him, right?? Is that not what the Word of GOD said? GOD blessed David with all, including multiple wives, and actually said that HE would've given David more if he wasn't satisfied. This was not just about the women, but this does not disregard the women either. You can't dissect and undermine GOD's blessings to David according to your cultural preferences.