Having recently hit 80 myself on my rogue, the only advice I can safely give is to use RAWR (
http://rawr.codeplex.com/) as a template and work from there. It'll give you an idea of specs to use, potential upgrades with best in slot advice as well as rotations. It's not perfect, but it's a starting point.
As one of my colleagues and peers mentioned though, sometimes you just have to go with gut feel on things and make up your own mind. There are plenty of tools out there that assist with enchant suggestions, gem suggestions, etc (be.imba.hu, etc) as well as in game mods like DirtyGear, GearDPS, RatingBuster, etc. Evaluate everything in terms of what you need most. If you want to just up DPS but run the risk of being a glass cannon, then tools like RAWR will tailor your upgrade and gem suggestions to match. If you tell it to increase overall rating, with added emphasis on DPS and Survivability, it'll change things around a bit. Evaluate all the advice then go with what you feel comfortable with.
Thus far, it's worked out well for me and in the few short days of playing and raiding as an 80 rogue with GS jumping from 2800 to 4000, I've rerun the tools and optimizations, etc. and I've noticed changes to suggested rotations, for example. As your character grows, so does it's DPS profile. You can rely more on some abilities and less on others. Again, work with what you're comfortable with. Try macro some of the rotations. Test them out on the dummies. See if you see a noticeable difference or not. Consider which poisons you're using, weapon speeds, etc.
This is what I've done both on my druid and on my rogue. It cuts out a lot of the guess work and it saves you wading through a bajillion theorycraft pages. Nothing stops you from doing that later though for fine tweaking but for the average joe who gets home from work and just wants to progress with the minimum of fuss and hassles, it'll do...
My 2 cents... You're welcome to disagree.