xdarlingnickyx is an author always good for fics that have warmth and cuddling and are long too. There is the requisite angst but the main focus is the slow building warm loving. IF you don't mind a/b/o universe. She's written others outside a/b/o universe and I bet they are just as good but I haven't read them yet. My favourite so far is
These Silent Hearts (http://xdarlingnickyx.livejournal.com/10691.html)
Summary : REQUEST: Jensen/Jared - self-lubrication, alpha/omega
The usual Alpha/Beta/Omega world set up.

In this world, the older, traditional family structure is a pack—usually between three and ten members, led by the head alpha and his beta mate, with maybe a couple other alpha and beta pairs, and then usually one or two omegas. Omegas are the only child bearing members of society. However, in the last couple of centuries, the "nuclear family' structure has caught on, and in modern times, the pack family is seen as outdated or archaic.

Jared doesn't care. He's known what he's wanted since he was a kid—to be the mated beta to the head alpha of a pack. The house mom, basically. He'd run the home, and look after everyone else in the pack. He's sure he'll turn out to be a beta, and even though he's been raised in the nuclear family style(born from artificial insemination to an omega surrogate), he wants to be part of a pack. When he hits puberty and wakes up in the throws of heat, with a soaking hole, and realizes he's an omega, he's heartbroken.

Fast forward to adulthood.

Jensen is the head alpha of a pack. He was born into a pack and loved living with so many different parents and caretakers, and so as an adult has formed his own. He has two mated alpha/beta pairs under him and an omega already under his care, but he doesn't have his own mate. Cue meeting Jared.

Omegas aren't mistreated, as a side note. They're cared for and loved, but don't really have jobs within the pack. They bear children and are looked after by the pack. The children tend to be raised by the group as a whole.

Up to author if Jared ends up accepting/enjoying being a pack omega or if the pack accommodates him and allows him to be head beta, as Jensen's mate, even though he's omega. Basically I want a big, loving, fluffy family—no abuse or degradation. Knot or do Knot, up to you.

Another author who used to write warm cuddly fics was fic_freaknout. I especially love Along the winding road (http://fic-freaknout.livejournal.com/tag/fic%3Aalong%20the%20winding%20road).