Multiplayer is going to be a tough requirement. There are not a lot of multiplayer games because Flash has been technologically handcuffed on that side for a while, and because most Flash game developers are indies who don't want to make that significant extra commitment.
A lot of Flash games launch without ads, you can get embed codes for a pretty fair selection of them here:
http://playtomic.com/games/catalog
For multiplayer games my friends at Nonoba (aka the Player IO guys which is the leading platform for multiplayer stuff for Flash games) are the ones you want to look at:
They have embed codes in the 'share' tab.