Been playing Reach for a while now (mostly offline, recently (one month so far) online).
Only very recently did I notice how missions in Reach nod to Halo CE. For instance:
Nightfall: This is a no brainer. Snipers? Check. At night? Check. Going to large Covenant presence? Check.
I loved this tribute but hated the mission (gameplay wise).
Long Night of Solace: Beach warfare. No other words needed.
Pillar of Autumn: You drive a mongoose on a path and do some jumps. Like the end mission of CE and 3. Less flood/explosions though.
Tell me if I missed any.