Hmm. I'm usually pretty reserved in suggesting units since I can't really know what the person posting actually owns/is able to proxy. Running with the ideas you just generated:
2x, 10-man tac squads w/ a heavy bolter and a flamer
inside drop pods with deathwind launchers
Drop Pods are my favourite thing ever, though in this list putting down Tactical marines might not be the most tactically sound. This is kinda the idea though: a 10 man squad in whatever transport you like, deploying 5 men on the table with the heavy weapon and deploying 5 men with the sergeant and assault weapon in the transport.
add a devastator squad with 2 lascannons and 2 missle launchers inside a razorback with plas/las and a hunter killer missile.
If you really want to put Devastator squads with only two heavy weapons on the table, why not use Rhinos? You could shoot those two weapons out of the top hatch while protecting your marines, though depending on your terrain available for games they might just be better in Ruins and the points for transports spent elsewhere (more weapons for your devastators!).