dw-frost for a min/maxer like the OP is very complex, so for him will be a lot of fun, as another pointed out a great dk will choose plague leach and blood tap(not macro'd) so you really have a lot to do, not only watching the boss mechanics and adds, but your swing timer, your runes, your diseases, all this while maintaining your priority rotation. anybody can dps as a dk, but not everyone can do great dps as a dk, unless you micro manage yourself, and min/max. so ya i think you'd love to play a dw-frost dk by the sounds of your original post.
unholy will be very viable in 5.2, its very easy to switch for awhile and see how you like the playstyle of unholy vs frost, i still play both, but i think you'll enjoy unholy more, at least if you get bored with one spec, you should be able to switch to a diff spec for awhile making them fun again, unlike monks where you just have one dps spec. dks will have 3 2-hand frost dw-frost and unholy